Hope someone has some advise, I have run out of ideas! I have a 92 f150 4x4 with a 5.0,and it idles really high it revs up quickly but it goes back down really slow and idles way to high. I have checked for vacuum leaks,intake manifold leaks,and removed and cleaned the IAC. I even replaced the IAC with a couple of other ones I have laying around. When engine is warmed up and I unplug the IAC the idle goes down,and once in a while it goes so low it stalls the motor but it starts right up. What could be the problem? I know these 302's very well but this one has me stumped. I want to thank you ahead of time for any help.

 

ya this is a pain I have the exact problem myself my IAC was pretty built up with carbon but after I cleaned it still no change. It almost seems to be higher now. going to start back at square one and check all vacuum lines and canisters and go from there. Ill keep you updated with what I find.

Sarge

 

Thanks Sarge,
I am going to do the same start from square one and see if I possibly missed something. If I find something out I will share it with you. I really hope my IAC isnt bad. They are quite expensive over 100 buck at auto zone, but I may have to buy a new one just to try it out. Pulled the one off my 89 mustang which I know works(at least it does fine on the HO 5.0) and i get same result. Oh well I will keep looking