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Discussion Starter #1
Good Afternoon! I recently purchased my first Bronco and I've been having issues with her since day one. She was stalling out at random times and not idling steady. She hates small incremental movements and always stalls reversing out of a parking lot but runs fine on the open road. I started with a much needed tune up, adjusting the timing, replacing a few relays, checking for any grounds and any issues with the fuel pump, with no joy. She's now been at the mechanics shop and he was baffled because he would get her running great but she'd die after idling for 20-30 minutes. The folks I bought her from said when they detailed the engine some water got into a relay switch but once they replaced it, she started up no problem. However, they didn't drive her much between when that happened and when I purchased her. Unfortunately I didn't test drive her first because I'm in the military and wasn't able to fly out to get her and bought sight unseen because the price was too good to pass up. She's in incredible shape if I could just get these kinks out. The mechanic is telling me the ECM needs replacing because it won't cycle from startup to operating mode. I'm not verse in ECM's, so I'm pretty much taking his word for it. The problem is when he pulled the ECM to get the program code, it had a Ford Taurus ECM. No doubt this ECM was re-programmed for the Bronco whenever it was installed but the program code physically on the computer is for the Taurus program. I've called Flagship One and Ford but both say they can't decode the VIN to get the program code for my particular Bronco because 87' is too old. The questions I have are the following: Do you think it's actually the ECM? Could detailing the engine have caused something in the old ECM to malfunction? Does anyone know how to find out which program my Bronco is running without that program code? Could the current ECM be plugged in to determine the code it's running? Lastly, my mechanic said the other option is changing from EFI to carb to bypass any computer issues all. This sounds like a really expensive and stupid idea to me. So I'm hoping y'all could point me in the direction to decoding the ECM or what else could be causing the issue. Thanks in advance for your advice!
 

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23,879 Posts
Yo Rosie87,
Welcome!
See EEC, (PCM ECU Computer) part numbers by smileybry & some catch codes by jowens1126 @ https://www.fullsizebronco.com/threads/fsb-ecu-part-number-the-definitive-list.64368/
Hopefully, we can use the info to source a yard queens EEC and/or have one purchase or tested, see below for EEC testers.

See VIN Decoding by NHTSA to identify engine size used when built @ https://vpic.nhtsa.dot.gov/decoder/?IsExport=False

For a YARD SEARCH on-line, I use;
https://www.hollanderparts.com
A yard that uses Hollander Interchange can search other yards and have it shipped.
"...For over eighty years, Hollander has been making the best tool for fast, interchangeable part matches. The new Edition Hollander Interchange contains more interchangeable options than ever before.
The Hollander Interchange provides auto recyclers and auto collectors, rebuilders, and others with the easiest and most comprehensive solution for identifying interchangeable auto parts..." See their yard Directory @: https://www.hollanderparts.com/SellerDirectory
Can select certain parts, including some Canadian yards.
Has Vehicle Pics for some vehicles
Search By: 1987 >Ford > Bronco > Electrical > Engine Motor Control Module >

Fitment
Compare these by engine size, etc according to your
Door Jamb Label, see typical pic with info pic in an 87 5.0
Source: by ChipW
151001

Note,this 87 was built according to Federal Emissions standards or California Emissions

Electronic Control Module, 6 300 (4.9L), AT, Federal
Electronic Control Module, 6 300 (4.9L), AT, High Altitude
Electronic Control Module, 6 300 (4.9L), MT, California
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E7TF K1A
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E7TF K1B
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E7TF K2A
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E7TF K2B
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E7TF KA
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E7TF KB
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E7TF L1A
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E7TF L1B
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E7TF L1C
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E7TF L2A
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E7TF L2B
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E7TF L2C
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E8TF CK1A
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E8TF CK2A
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E8TF CL1A
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E8TF CL2A
Electronic Control Module, 6 300 (4.9L), MT, High Altitude
Electronic Control Module, 8 302 (5.0L), AT, California
Electronic Control Module, 8 302 (5.0L), AT, Federal, ID E7TF AT1B
Electronic Control Module, 8 302 (5.0L), AT, Federal, ID E7TF AT2B
Electronic Control Module, 8 302 (5.0L), AT, Federal, ID E7TF AV1A
Electronic Control Module, 8 302 (5.0L), AT, Federal, ID E7TF AV2A
Electronic Control Module, 8 302 (5.0L), AT, Federal, ID E7TF BA1A
Electronic Control Module, 8 302 (5.0L), AT, Federal, ID E7TF BA2A
Electronic Control Module, 8 302 (5.0L), AT, Federal, ID E7TF BC1A
Electronic Control Module, 8 302 (5.0L), AT, Federal, ID E7TF BC2A
Electronic Control Module, 8 302 (5.0L), AT, Federal, ID E7TF BCA
Electronic Control Module, 8 302 (5.0L), AT, Federal, ID E8TF J1A
Electronic Control Module, 8 302 (5.0L), AT, Federal, ID E8TF J2A
Electronic Control Module, 8 302 (5.0L), AT, Federal, ID E9TF AL1A
Electronic Control Module, 8 302 (5.0L), AT, Federal, ID E9TF AL2A
Electronic Control Module, 8 302 (5.0L), MT
Ignition Control,
Alternate Engine Motor Control Module

Hopefully other 87 owners will chime in with their EEC Replacement INFO
¤
or

http://www.car-parts.com/
Can select certain parts
Can search by year range, such as 92 through 96 & has best item condition descriptions such as "COVER BAD LEATHER PWR BKT GRY"
Has Vehicle Pics for some vehicles incl. interior/dash, back seat, front & rear and engine bay
□°□

Although relatively inexpensive, I would avoid Cardone reman PCMs.
Consider;
AES Modules @ AES Modules | Rebuilt & Reman Control Modules

ProTech Auto Systems @ Ford Car Computer Repairs for ECU, PCU & TCU
¤
➡➡➡ jermil01 wrote, "In the past I've bought an EEC from these guys before. Good service and fast turn around. Plug in your info and you'll quickly find what you're looking for: Price is pretty reasonable.."
https://www.autocomputerexchange.com/419/1995-ford-bronco-5-8l-v8-gas-ecm-pcm.html

Rolling Idle, No code perps;
First, Intake Air Temp (IAT); (Air Charge Temperature [ACT] prior to 1992)

"Before you start blaming the air charge temperature sensor and replacing it make sure the rest of the coolant system is in good condition. All of the following items will affect the ACT:
•Coolant level
•Radiator Fan
•Engine Temperature

•Ambient temperature
•Air Filter
•Air Filter to Throttle Body Duct
•Water pump and Fan Belts
•Thermostat
•EGR System
•Engines general condition
•Harness and wire general condition
The Air Charge Temperature (ACT) sensor is a thermal transistor, which means it allows less electricity to pass through the sensor the warmer it gets. The ACT receives the Signal Return voltage from the EEC, and then allows a certain amount to return back to the EEC. Because the ACT is mounted into the incoming air stream it changes resistance in response to the temperature of that air.
temperature graph

The ACT sensor is very important when calculating fuel ratios and timing curves. This is because of simply chemistry; fuel and spark are constants in the equation. Air is the biggest variable in combustion; it changes density greatly over a range of temperature. So keeping track of the changing temperatures of the incoming air and the engine in which it is burnt becomes very important. But due to its simplicity of design, the ACT is rarely at fault when problems occur.
Before testing the ACT or any other EFI component perform a self-test, trouble codes received during test can be used as a diagnostic tool along with other indicators. To test an ACT sensor you will need a volt meter. You can test the ACT by back probing the harness while reading the voltage returning to the EEC. Or you can removing the connector completely and test the resistance between the 2 pins on the ACT. The ambient temperature should be above 50F (10C) to receive acceptable input from the Air Charge Temperature (ACT) sensor during the KOEO and KOER Self-Test. To accomplish this, the engine should be at normal operating temperature.
SEE THE GRAPH @ Fuel Injection Technical Library » Air Charge Temperature (ACT)


Values were calculated for VREF=5.0 volts.These values may vary 15 percent due to
sensor and VREF variations
by Ryan M
...
One way to do a quick check is to grab a vacuum gauge. Bring the engine to normal operating temperature. Connect gauge to the intake manifold tee. BEWARE OF FAN, BELT, PULLEYS & HIT ENGINE.
The vacuum gauge should read between 15 and 22 in-Hg depending upon the engine condition and the altitude at which the test is performed. SUBTRACT ONE INCH FROM THE SPECIFIED READING FOR EVERY 1,000 FEET OF ELEVATION ABOVE SEA LEVEL.
The reading should be quite steady. .

When engine is rapidly accelerated (dotted needle), needle will drop to a low (not to zero) reading. When throttle is suddenly released, the needle will snap back up to a higher than normal figure.

When vacuum leaks are indicated, search out and correct the condition. Excess air leaking into the system will upset the fuel mixture and cause conditions such as rough idle, missing on acceleration, or burned valves. If the leak exists in an accessory unit, such as the power brake, the unit will not function correctly.
➡Or Air Conditioning when in MAX mode may switch to Defrost.


Try unplugging the Idle Air Control (IAC)
Testing..
"First let me say this little thing has many names. But they all talk about the same item under the hood. Here all the names I've had the torture of learning throughout the years:
•Idle Air Bypass •Idle Air Control •Idle Speed Control •Throttle Bypass Air •Idle Bypass •Inlet Air Controller
•Inlet Air Bypass •Intake Air Bypass •Intake Air Control.
This is really easy to test. First as with all problems you should gather the trouble-codes from the computer. Follow the codes for testing and repair. If you get a code that points to a problem with the IAB start the vehicle and bring the engine up to operating temperature. Allow the engine to idle without any driver input to the throttle or pedal. Go under the hood, and disconnect the electrical connector to the IAB. If the engine begins to stubble or stalls the IAB is functional and does not need to be repaired. If the engine idle does not change you should remove the IAB for inspection.
The IAB can pass and still need repair, or it can fail and not need replacing. The plunger and internal spring can get clogged with dirt and oil. This will slow down the air flow and not allow the IAB to function properly. Remove the IAB and clean it. There are 2 halves to the IAB, and you can not buy just one half, but you can take it apart to clean it. But if the internal solenoid is faulty the IAB needs to be replaced." By Ryan M.
...
This is by Nelbur; "I have spent some time this week trying to set up an air bypass around the IAC valve by cutting away some of the gasket between the IAC in and out air holes, rather than pay big bucks for Fords spacer kit. I cut away the center of the original IAC gasket from the outside of each hole to the outside of the other hole, giving about 1/2" gap for the air to pass through. I noticed an immediate improvement in the engines starting behavior, but it would still die occasionally.

It would rev up and then drop the idle so low it would die unless I would catch the idle with the accelerator. ... ...
I decided that more improvement could be had if I had a thicker gasket, because the original IAC gasket was very thin (0.018"). I had some 0.030" gasket material so I made my own with the same 1/2" cut out. This gave enough bypass to noticeably raise the idle speed and almost eliminate the dying. After maybe 50 starts in the last few days, it only died twice. After so many years of catching it with the accelerator it is darned hard to leave my foot off it. It is clear to me that by trial and error one can tune the air bypass without the need for the expensive Ford kit. I may combine the two gaskets for more bypass, but the idle is about as fast as I would want now, especially for driving in snow."

Idle Air Control (IAC) Sludge; Poor Idle TSB 91-25-07 for 85-92 Bronco & F Series & many others; "...Hard cold starts, hesitation and stalls on initial start-up or during idle or decel may be caused by sludge in the throttle body and/or idle by-pass valve. Sludge deposits or oil film on the throttle body bore and plate or the idle air by-pass valve may cause one or more of the following conditions. Hard Cold Start, Stall On Initial Start-Up, Stall During Idle, Stall During Decel, Rough Idle, Rolling Idle, Hesitation During Acceleration. A new idle air by-pass service kit (F2PZ-9F939-A) is now available for service use to correct sludge contamination concerns of the throttle bore and plate only. It eliminates the need to clean the majority of past model throttle body applications. Cleaning is not required on sludge tolerant throttle body designs released for 1991 and newer model years..."
Buy a Motorcraft IAC in event it needs to be replaced.
●⊙●
See "1987 Ford Bronco Catalog, "Great Go-Togethers, Eddie Bauer and Ford Bronco"" by Ford @ https://www.thehenryford.org/collections-and-research/digital-collections/artifact/368502/#slide=gs-223716

1987 Owner's Manual, partial (Towing it & 4 speed manual transmission shift patterns & operation) by Ford via Mikey350 @ https://www.supermotors.net/registry/23082/86378-2

For any questions or to chat about it's planned modifications, it's better to post each seperately in Noobie Bronco Tech Questions. Flame free zone. This will get more attention and you can build up your post count to get into other sections such as Bronco and Ford Parts/Accessories (75 posts required to view).

To save you time and for better responses, please fill out your Signature with location, year, engine size, transmission type, transfer case type (manual or electric shift), locking hub type (automatic or manual) info & major mods such as a Lift, etc. .
From the navigation, near the upper right-hand corner, click on your avatar and then select “Account Settings” from the drop down menu.

From your “Account Settings” page you will then see more navigation option of the left side. Select “Signature”.

Now you can simply enter your signature information in the text editor and click save.

Our Forum faqs @ https://www.fullsizebronco.com/help/faq/
Includes for example:
How To Upload Images To Posts & How to Use Search
See more tips!

Baba Looey's Favorite FSB Links (lots and lots of tech links) @ https://www.fullsizebronco.com/forum/21-noobie-bronco-tech-questions-flame-free-zone/131287-baba-looeys-favorite-fsb-links-lots-lots-tech-links.html

Free registration for some wiring diagrams (86 through 96) and Technical Service Bulletins, (80 through 96), same as by Ford @ BBB Industries- Premium Alternators, Starters, Power Steering Products | TSB's & Wiring Diagrams

➡Please try to take time to Participate and Vote in our Full-Size of the Month (F.O.T.M.) & Full-Size of the Year (F.O.T.Y.) Contests @ https://www.fullsizebronco.com/forum/27-f-o-t-m-voting/
F.O.T.Y. Contests will be held in JANUARY, MARCH, MAY, JULY, & SEPTEMBER. Each month in-between will be used for nominating contestants to run in the following Month.
You will get ideas by those competing. Also see the prizes! They are awesome as compared to other sites' "contests"!
VOTE ASAP IN ONGOING the Full-Size of the Year (F.O.T.Y.) CONTEST!

Al
 

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Registered
1984, 300 L6, smogless, manual 3speed with overdrive.
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711 Posts
Are they year specific or model specific. Broncos are harder to come by in the jy’s then pickups or vans. I’m guessing they used the same programs across those platforms? Would give better odds for finding one if they did. I’m old school give me a carb over EFI any day.
 

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MidlifeCrisisUndrWay
Joined
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1,688 Posts
OP,
Google 'wall of text'
 

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Registered
Joined
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1,699 Posts
We totally dumped the EECIII ignition system in my 82 and installed a universal GM ignition system. Maybe u can do something similar if the 87s ignition system is as unreliable as the 82 was. Certainly sounds easier then going from efi to carb
 

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Registered
Joined
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3 Posts
Discussion Starter #6
Yo Rosie87,
Welcome!
See EEC, (PCM ECU Computer) part numbers by smileybry & some catch codes by jowens1126 @ https://www.fullsizebronco.com/threads/fsb-ecu-part-number-the-definitive-list.64368/
Hopefully, we can use the info to source a yard queens EEC and/or have one purchase or tested, see below for EEC testers.

See VIN Decoding by NHTSA to identify engine size used when built @ https://vpic.nhtsa.dot.gov/decoder/?IsExport=False

For a YARD SEARCH on-line, I use;
https://www.hollanderparts.com
A yard that uses Hollander Interchange can search other yards and have it shipped.
"...For over eighty years, Hollander has been making the best tool for fast, interchangeable part matches. The new Edition Hollander Interchange contains more interchangeable options than ever before.
The Hollander Interchange provides auto recyclers and auto collectors, rebuilders, and others with the easiest and most comprehensive solution for identifying interchangeable auto parts..." See their yard Directory @: https://www.hollanderparts.com/SellerDirectory
Can select certain parts, including some Canadian yards.
Has Vehicle Pics for some vehicles
Search By: 1987 >Ford > Bronco > Electrical > Engine Motor Control Module >

Fitment
Compare these by engine size, etc according to your
Door Jamb Label, see typical pic with info pic in an 87 5.0
Source: by ChipW
View attachment 151001
Note,this 87 was built according to Federal Emissions standards or California Emissions

Electronic Control Module, 6 300 (4.9L), AT, Federal
Electronic Control Module, 6 300 (4.9L), AT, High Altitude
Electronic Control Module, 6 300 (4.9L), MT, California
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E7TF K1A
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E7TF K1B
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E7TF K2A
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E7TF K2B
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E7TF KA
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E7TF KB
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E7TF L1A
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E7TF L1B
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E7TF L1C
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E7TF L2A
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E7TF L2B
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E7TF L2C
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E8TF CK1A
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E8TF CK2A
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E8TF CL1A
Electronic Control Module, 6 300 (4.9L), MT, Federal, ID E8TF CL2A
Electronic Control Module, 6 300 (4.9L), MT, High Altitude
Electronic Control Module, 8 302 (5.0L), AT, California
Electronic Control Module, 8 302 (5.0L), AT, Federal, ID E7TF AT1B
Electronic Control Module, 8 302 (5.0L), AT, Federal, ID E7TF AT2B
Electronic Control Module, 8 302 (5.0L), AT, Federal, ID E7TF AV1A
Electronic Control Module, 8 302 (5.0L), AT, Federal, ID E7TF AV2A
Electronic Control Module, 8 302 (5.0L), AT, Federal, ID E7TF BA1A
Electronic Control Module, 8 302 (5.0L), AT, Federal, ID E7TF BA2A
Electronic Control Module, 8 302 (5.0L), AT, Federal, ID E7TF BC1A
Electronic Control Module, 8 302 (5.0L), AT, Federal, ID E7TF BC2A
Electronic Control Module, 8 302 (5.0L), AT, Federal, ID E7TF BCA
Electronic Control Module, 8 302 (5.0L), AT, Federal, ID E8TF J1A
Electronic Control Module, 8 302 (5.0L), AT, Federal, ID E8TF J2A
Electronic Control Module, 8 302 (5.0L), AT, Federal, ID E9TF AL1A
Electronic Control Module, 8 302 (5.0L), AT, Federal, ID E9TF AL2A
Electronic Control Module, 8 302 (5.0L), MT
Ignition Control,
Alternate Engine Motor Control Module

Hopefully other 87 owners will chime in with their EEC Replacement INFO
¤
or

http://www.car-parts.com/
Can select certain parts
Can search by year range, such as 92 through 96 & has best item condition descriptions such as "COVER BAD LEATHER PWR BKT GRY"
Has Vehicle Pics for some vehicles incl. interior/dash, back seat, front & rear and engine bay
□°□

Although relatively inexpensive, I would avoid Cardone reman PCMs.
Consider;
AES Modules @ AES Modules | Rebuilt & Reman Control Modules

ProTech Auto Systems @ Ford Car Computer Repairs for ECU, PCU & TCU
¤
➡➡➡ jermil01 wrote, "In the past I've bought an EEC from these guys before. Good service and fast turn around. Plug in your info and you'll quickly find what you're looking for: Price is pretty reasonable.."
https://www.autocomputerexchange.com/419/1995-ford-bronco-5-8l-v8-gas-ecm-pcm.html

Rolling Idle, No code perps;
First, Intake Air Temp (IAT); (Air Charge Temperature [ACT] prior to 1992)

"Before you start blaming the air charge temperature sensor and replacing it make sure the rest of the coolant system is in good condition. All of the following items will affect the ACT:
•Coolant level
•Radiator Fan
•Engine Temperature

•Ambient temperature
•Air Filter
•Air Filter to Throttle Body Duct
•Water pump and Fan Belts
•Thermostat
•EGR System
•Engines general condition
•Harness and wire general condition
The Air Charge Temperature (ACT) sensor is a thermal transistor, which means it allows less electricity to pass through the sensor the warmer it gets. The ACT receives the Signal Return voltage from the EEC, and then allows a certain amount to return back to the EEC. Because the ACT is mounted into the incoming air stream it changes resistance in response to the temperature of that air.
temperature graph

The ACT sensor is very important when calculating fuel ratios and timing curves. This is because of simply chemistry; fuel and spark are constants in the equation. Air is the biggest variable in combustion; it changes density greatly over a range of temperature. So keeping track of the changing temperatures of the incoming air and the engine in which it is burnt becomes very important. But due to its simplicity of design, the ACT is rarely at fault when problems occur.
Before testing the ACT or any other EFI component perform a self-test, trouble codes received during test can be used as a diagnostic tool along with other indicators. To test an ACT sensor you will need a volt meter. You can test the ACT by back probing the harness while reading the voltage returning to the EEC. Or you can removing the connector completely and test the resistance between the 2 pins on the ACT. The ambient temperature should be above 50F (10C) to receive acceptable input from the Air Charge Temperature (ACT) sensor during the KOEO and KOER Self-Test. To accomplish this, the engine should be at normal operating temperature.
SEE THE GRAPH @ Fuel Injection Technical Library » Air Charge Temperature (ACT)


Values were calculated for VREF=5.0 volts.These values may vary 15 percent due to
sensor and VREF variations
by Ryan M
...
One way to do a quick check is to grab a vacuum gauge. Bring the engine to normal operating temperature. Connect gauge to the intake manifold tee. BEWARE OF FAN, BELT, PULLEYS & HIT ENGINE.
The vacuum gauge should read between 15 and 22 in-Hg depending upon the engine condition and the altitude at which the test is performed. SUBTRACT ONE INCH FROM THE SPECIFIED READING FOR EVERY 1,000 FEET OF ELEVATION ABOVE SEA LEVEL.
The reading should be quite steady. .

When engine is rapidly accelerated (dotted needle), needle will drop to a low (not to zero) reading. When throttle is suddenly released, the needle will snap back up to a higher than normal figure.

When vacuum leaks are indicated, search out and correct the condition. Excess air leaking into the system will upset the fuel mixture and cause conditions such as rough idle, missing on acceleration, or burned valves. If the leak exists in an accessory unit, such as the power brake, the unit will not function correctly.
➡Or Air Conditioning when in MAX mode may switch to Defrost.


Try unplugging the Idle Air Control (IAC)
Testing..
"First let me say this little thing has many names. But they all talk about the same item under the hood. Here all the names I've had the torture of learning throughout the years:
•Idle Air Bypass •Idle Air Control •Idle Speed Control •Throttle Bypass Air •Idle Bypass •Inlet Air Controller
•Inlet Air Bypass •Intake Air Bypass •Intake Air Control.
This is really easy to test. First as with all problems you should gather the trouble-codes from the computer. Follow the codes for testing and repair. If you get a code that points to a problem with the IAB start the vehicle and bring the engine up to operating temperature. Allow the engine to idle without any driver input to the throttle or pedal. Go under the hood, and disconnect the electrical connector to the IAB. If the engine begins to stubble or stalls the IAB is functional and does not need to be repaired. If the engine idle does not change you should remove the IAB for inspection.
The IAB can pass and still need repair, or it can fail and not need replacing. The plunger and internal spring can get clogged with dirt and oil. This will slow down the air flow and not allow the IAB to function properly. Remove the IAB and clean it. There are 2 halves to the IAB, and you can not buy just one half, but you can take it apart to clean it. But if the internal solenoid is faulty the IAB needs to be replaced." By Ryan M.
...
This is by Nelbur; "I have spent some time this week trying to set up an air bypass around the IAC valve by cutting away some of the gasket between the IAC in and out air holes, rather than pay big bucks for Fords spacer kit. I cut away the center of the original IAC gasket from the outside of each hole to the outside of the other hole, giving about 1/2" gap for the air to pass through. I noticed an immediate improvement in the engines starting behavior, but it would still die occasionally.

It would rev up and then drop the idle so low it would die unless I would catch the idle with the accelerator. ... ...
I decided that more improvement could be had if I had a thicker gasket, because the original IAC gasket was very thin (0.018"). I had some 0.030" gasket material so I made my own with the same 1/2" cut out. This gave enough bypass to noticeably raise the idle speed and almost eliminate the dying. After maybe 50 starts in the last few days, it only died twice. After so many years of catching it with the accelerator it is darned hard to leave my foot off it. It is clear to me that by trial and error one can tune the air bypass without the need for the expensive Ford kit. I may combine the two gaskets for more bypass, but the idle is about as fast as I would want now, especially for driving in snow."

Idle Air Control (IAC) Sludge; Poor Idle TSB 91-25-07 for 85-92 Bronco & F Series & many others; "...Hard cold starts, hesitation and stalls on initial start-up or during idle or decel may be caused by sludge in the throttle body and/or idle by-pass valve. Sludge deposits or oil film on the throttle body bore and plate or the idle air by-pass valve may cause one or more of the following conditions. Hard Cold Start, Stall On Initial Start-Up, Stall During Idle, Stall During Decel, Rough Idle, Rolling Idle, Hesitation During Acceleration. A new idle air by-pass service kit (F2PZ-9F939-A) is now available for service use to correct sludge contamination concerns of the throttle bore and plate only. It eliminates the need to clean the majority of past model throttle body applications. Cleaning is not required on sludge tolerant throttle body designs released for 1991 and newer model years..."
Buy a Motorcraft IAC in event it needs to be replaced.
●⊙●
See "1987 Ford Bronco Catalog, "Great Go-Togethers, Eddie Bauer and Ford Bronco"" by Ford @ https://www.thehenryford.org/collections-and-research/digital-collections/artifact/368502/#slide=gs-223716

1987 Owner's Manual, partial (Towing it & 4 speed manual transmission shift patterns & operation) by Ford via Mikey350 @ https://www.supermotors.net/registry/23082/86378-2

For any questions or to chat about it's planned modifications, it's better to post each seperately in Noobie Bronco Tech Questions. Flame free zone. This will get more attention and you can build up your post count to get into other sections such as Bronco and Ford Parts/Accessories (75 posts required to view).

To save you time and for better responses, please fill out your Signature with location, year, engine size, transmission type, transfer case type (manual or electric shift), locking hub type (automatic or manual) info & major mods such as a Lift, etc. .
From the navigation, near the upper right-hand corner, click on your avatar and then select “Account Settings” from the drop down menu.

From your “Account Settings” page you will then see more navigation option of the left side. Select “Signature”.

Now you can simply enter your signature information in the text editor and click save.

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Al
Wow thanks so much for all the information!
 

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Update: it was the MAP sensor. I changed that out and she started running great!
Good to hear! Also, if you even need an EEC try O'reilly. The Master Pro has a line of EECs that are programed based on Engine and transmission combos. Don't need to give them your vin to get them programed. Just year, engine and transmission.
 

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I find it hard to believe a ECM/PCM for a Taurus would ever run an engine in a Bronco. Your "mechanic" most likely looked up the engineering number, example E7TF-12A650-AUB, then saw hundreds of hits because all Ford ECM/PCMs use the same base number (12A650). There is no re-programming possible for this vintage of engine control modules.

Check the driver side B-pillar to see if the Calibration Code sticker is still there.

courtesy of Subford

Some folks have the documentation to lookup what the engineering number is based off the Calibration Code.This is the computer the truck came from the factory.
 
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