Hey, i don't see your sig, so let's start from the beginning.

What are you mods?
When did this problem start? Was is doing it before or after you installed a part?
Have you removed anything? Added anything? Has anything changed?

Just trying to get an idea here,

maybe all of us can get this fixed.

Also, the iac is a pita, if it's been removed or messed with it'll need to perform kind of a relearn, go drive your truck and do some stop and go and cycle the ignition a few times, if you did already, oh well, we'll see what's on the list to check next.

allen