Big_Swede

The car; AC Cobra (factory five racing)
The engine; Ford SVT Cobra dohv 281 cid -98, stock ECU

The problem; Im having problems with my idle rpm. The car behaves normally and settles at an idle speed at about 800 rpm. But all of a sudden when driving and shifting to another gear, the idle shoots up to 2500-3000 rpm. The only solution to this problem is to turn the ignition off and restart the car.
Another problem im having is that the idle stays fairly high almost every time im shifting to another gear. In other words, even when i reach 800 rpm at idle, it takes an aweful long time for the engine to settle at this range. At least 5 seconds.

Done so far:
Replaced the IAC (Ford OEM)
Checked error codes with my OBD-reader (no errors)
Checked the voltage to the IAC.

Im lost as of now, and need assistance in finding whats wrong with the engine. Faulty throttle body? Faulty tps? Vacuum leak? I need help!

And pardon my bad english..im from Sweden

Vertigo_GT

Bad English? Hell, you wrote the most grammatically correct post I have seen in this forum. I hope someone solves your idle problem soon. There are some pretty savvy members here that I am sure will give you some likely culptrits and suggestions.

Derf00

Did you buy the car used or did you put it together yourself?

Big_Swede

I just remembered, the ECU has been re-programmed since the EGR is deleted.

And i bought the car fully built. The engine came from a -98 Cobra which had been left on the junkyard for some time.

uberstang1

Possibly the throttle positioning sensor.