Aleakydishwasher

Girlfriend drives an 02 F150 with the 4.6L. It ran like a top until recently it started to idle very high at a warm start (2000rpm) for about 20 seconds before dropping to normal. Eventually it started to surge up and down from idle to 2000rpm and became difficult to drive. It was almost like having a stuck throttle. Finally it would rev up and down and stall out.

My first thought was to replace the Idle Air Control valve. This worked wonders and the truck would at least run again. It still idles high (1500rpm) but will eventually drop to idle and still pulls while coasting in gear, if I drop into neutral it will eventually drop to idle.

I hooked a diagnostic tool to it and looked at the throttle position sensor readings and they are normal and consistent weather or not it is idling normally or high. I sprayed with starting fluid (engine cold) to look for vacuum leaks and found none.

I will also add that at no point has it thrown a code.

Any ideas?