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Hi all, I finally got a new motor in my '95 Bronco and now I have an issue. First off, I have a standard bore 5.8 engine with flat top pistons, Comp Cam 35-349-8, GT40 heads, long tube headers into single 3 inch exhaust. I have replaced ALL sensors with the exception of MAP, IAC and TPS. My issue is that the engine runs great with the exception of a surging idle around 200 rpm difference (600-800). The surging I can live with but as soon as I touch the gas pedal with my finger and BARELY move it she will die. I can floor it and it stumbles a little then works fine but it will die as soon as I let off the throttle. It starts right back up and idles as stated above. I have tested both the IAC and TPS and they both are within the specs. Throttle body and IAC have also been cleaned. Timing is at 10* and plugs are gapped at .050 or whatever the sixlitre tune up called for. I know the timing is supposed to be set at 14* with the plugs gapped that wide but is that an issue? I did use the MSD coil that puts out 45,000 volts and yes I used Motorcraft Racing 9mm plug wires and Motorcraft cooper plugs. I have not replaced the fuel filter or checked fuel pressure but that is on the to do list for tomorrow, I did however install a new fuel pump. I have also replaced all the vacuum lines and checked for leaks with none found. I am also checking to see what kind of vacuum I have as soon as I get my gauge back from my friend. What am I missing? Where do I go from here?

Thanks
Scott
Ford has always had some crazy vacuum lines. Leave the vacuum hooked up to your coil and pull the other end off and suck on it. You should have resistance, if not not you need to look into your coil.
 

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Discussion Starter #22
That REALLY ticks me off! I did what you suggested 85bronco86 and it is leaking vacuum. What gets me though is that I had EVERYTHING disconnected from the vacuum tree except the MAP and the EGR testing the other day. I could have saved myself alot of headache and time if I had only disconnected the EGR. Thanks for the help all and hopefully I'll be good now if only I can get the ABS to bleed!!!
 

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Yo Scott,
If EGR valve is stuck open, it will essentially cause a vacuum leak, leading to inefficient combustion, rough idling, hesitation & sometimes stalling.

159738
 

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