I have an 1987 2.8L V6 MPFI. and my car idles very high unless I step on the gas to rev the motor up, then it returns to normal. But if I creep up (drive) even a tiny bit, I again have to rev the motor up, and the rpms will come back down. If I rev high enough the car backfires on me. And sometimes while accelerating and shifting into 2nd gear it will backfire aswell.

Ive tryed a new IAC, a new throttle body/gasket, Ive taken out all of the injectors and checked all the seals they look ok but maybe I should replace them, replaced all of the upper intake gaskets. I dont throw any codes.

If anyone has any idea on what is causing this. please post I am forever stumped on what is wrong. Thanks!

Craig

Craig,
How are the plugs, do you foul any ? Any chance of a vacuum leak ? And yes possibly an intake gasket, good way to check that is while its running spray something like wd 40 or even water around the gasket, it will seal the leak (if there is one) just for a moment causing the idle to smooth out. The IAC was my first thought...but you already replaced it.

Dennis

Craig, Check your timing and also as Dennis suggested to check for a vacuum leak. Check all your vacuum lines as well and around the intake manifold.