Everyone I have 02 F150 with a 5.4 that when cold or on first short trip the idle flucuates up and down. I start it, let the truck idle back down to around 600 then drive it. Upon returning to a stop or putting the truck in Park the idle searches between 600-900 rpms. A little press on the accelerator straightens things out. Is this a sign of something on the way out like the IAC. I cleaned and checked the throttle body butterfly, the PCV, and removed the IAC and cleaned it with some throttle body cleaner. The problem still exists. Any help would be appreciated?

Thanks

 

It sounds like an IAC valve, but I guess it could be a vacuum leak. If you've cleaned the IAC I'd look elsewhere, but I've heard of cleaned IACs still being messed up.

You'll have to let the vacuum experts take it from here.

Mike

 

It sounds to me like it an probaly with the IAC, cleaning it sometimes works but doesn't always, remember that. However if you have cleaned everything good then i agree, go through check all your vacume hoses for cracks, check your pcv valve, ect. Im sure someone else will post up with more info about th vacuum as im not sure on them either