I have a 94 with a 302 manual trans. I've been chasing an idle issue for a week now. It was loping bad at idle and I've tested, checked and/or replaced everything I can think of.

I finally replaced the IAC valve when I found that is was stuck open. Looks to me like the loping is caused by leaning out from IAC being open and letting too much air in. With the new one installed it idles good at start up but then the IAC started opening and closing randomly and when ever it opens the engine lopes again.

Do I need to reset the PCM or is there a faulty sensor telling it to open when it shouldn't.

 

Yes it needs to relearn the idle.

 

I disconnected the battery for about 10 minutes last night and tried again with the same result. Is there another way to reset the PCM?

 

Leave battery disconnected minimum of 15 mins

It may take a couple hundred miles of driving for it to relearn.

 

Make a restrictor plate for it.

 

https://www.f150forum.com/f10/when-a...g-idle-199406/

 

Thanks for the input. I may try driving it for a bit to see if it relearns the idle. In the mean time I am going to fab up the restrictor plate (thanks for the link to the instructions). And if the problem persists I will try the plate and go from there.

I appreciate the help