When starting the engine rev’s to 3200 rpm then goes down to around 900. When driving it will rev to 2200 rpm’s and won’t go down. I have changed the throttle position sensor, air control valve and now it’s worse then before. Our mechanic saw no error codes and shakes his head saying never seen this before. Any help would be appreciated.

 

Your truck is basically a Ford Ranger......so definitely look at some Ford Ranger sites and I'll bet you'll find all kinds of "High Idle Issue" threads on those sites.

One of the first things that I would do is to look for ANY vacuum leaks and fix them if you find any......cracked vacuum hoses, PCV valve & vacuum hose, EGR & vacuum hose, etc.
You may want to check the O2 sensor also.....if it is bad, it could cause idle issues. If it is working properly, and you do have a vacuum leak somewhere (or intake air leak), the O2 sensor will send a LEAN CONDITION signal to the engine computer and the computer will tell the injectors to add more fuel (even at idle), therefore creating a high idle situation.

Make sure you are not leaking air at the new Idle Air Control that was installed.......chances are good, that it is a simple issue that is causing your problems.

Let us know what you find out, and welcome to the forum!