Try a Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19
The engine temperature must be greater than 50° F for the Key On Engine Off (KOEO) Self-Test and greater than 180° F for the Key On Engine Running (KOER) Self-Test.
Run it around to heat the engine up and shift thru all gears incl Reverse. Then turn off all accessories/lights, etc.
Make sure A/C is off and transmission is in Park (automatic) or in Neutral for a Manual & release clutch.
Do Key On Engine Off (KOEO) portion first.
Look Codes up in my broncolinks.com site using the new Search function.
And Post em here according to:
Is Transmission Control Indicator Light (Overdrive On/Off Switch) blinking?
Fluid Condition and Torque Converter Shudder/Slip with no DTCs; "...proper operation of Ford transmissions is supremely dependant on ATF condition. The Mercon fluid has certain additives that regardless of apparent condition of the fluid, wear out. He claimed the average driver pays little attention to the slight slipping that begins to occur as the fluid ages and allows it to continue, causing the fluid to get dark and burnt smelling. As this happens, the fluid loses more of it's ability to provide the necessary function plus the degraded fluid begins to attack the rubber internal parts. Time for a rebuild due to not changing fluid when called for. A different scenario unfolds with very conservative drivers (like the elderly gent whom I bought my Bronco from). They may tool around so gently that the trans never slips. In this case, the fluid continues to look and smell fine but when someone else starts driving more aggressively, it appears the trans/tc is failing when all along it's really the depleted fluid which doesn't have to look/smell bad to be bad. His suggestion was to do the 20 quart flush at the cooler line and add any of the common friction modifiers they sell. Did that and night and day difference. No tc shudder/slip and trans shifts like new..."
Source: by Gary M at FSB
Shift Point Road Test
This test verifies that the shift control system is operating properly. for a 96 but =
Shudder; "...If the shudder occurs a) during the 3-4 or 4-3 shift at HEAVY throttle, or b) at 40mph in 2, OD OFF, and OD, or c) at the same RPM in every gear, or d) coasting, cruising, or in R, or e) during extended light braking, then it is NOT TC clutch shudder; The following is a list of common vehicle concerns that have been misdiagnosed as torque converter clutch shudder. For diagnosis of the following items, refer to the appropriate sections of the workshop manual and the Powertrain Control/Emissions Diagnosis manual (PCED). Spark plugs - check for cracks, high resistance or broken insulators. Plug wires. Fuel injector - filter may be plugged. Fuel contamination - engine runs poorly. EGR valve - valve may let in too much exhaust gas and cause engine to run lean. Vacuum leak - engine will not get correct air/fuel mixture. MAP/MAF sensor - improper air/fuel mixture. HO2S sensor - too rich/lean air/fuel mixture. Fuel pressure - may be too low. Engine mounts -loose/damaged mounts can cause vibration concerns. Axle joints - check for vibration..."
Source: by Steve83 (Steve, That dirty old truck) at SuperMotors.net