I changed the IAC valve 2 months ago because my truck kept stalling when idling down on a cold start and that fixed the problem.
A few days days ago when starting it started revving to 2 - 3 K and won't IDLE down now? I changed the IAC again and that didn't help. What else should I be looking at to stop it from revving so high?
Thanks
2001 F250 5.4 111,000 miles super duty.

 

Vacuum leak most likely. Common on those is the PCV hose and elbow. Follow it from the valve back to the intake. If not there, intake gaskets are possible too.

 

OK Fixed again.
It was the TPS sensor I bought a new one just to try it and fixed the problem.