I have a 99 Contour with the 2.5 auto. It idles at about 1100 rpm and when in drive, creeps up to 1700 with no gas pedal applied. In the morning when it's cold, the first time you start it, the rpms jump up to 2000 and then drop to nothing and it stalls out. I'm picking up a 1506 code (Idle Overspeed).

I've replaced the TPS and IAC. Any thoughts?

 

A good place to start is see if you have any vacuum leaks. the evap canister valve may be stuck open, Inspect the entire intake system from mass air flow sensor(MAF) to the intake manifold for damage or leaks. It sounds like extra air is getting into the system and the computer is trying to correct a lean condition. Where all incoming air is measured by the MAF and fuel is adjusted accordingly additional unmeasured air may be causing the ECM to attempt to correct a lean mixture.

 

Thanks for your advice. I was thinking vacuum leak as well. I've done a trace back (as best I can) from the MAF but didn't see, hear or feel any leaks. Everything seemed attached and no split lines. However, I didn't check the canister. According to Chilton's, it's located under the spare tire well at the back of the car. Where is the valve for it?

Thanks.

 

The only suggestion I can offer at this time is , trace the line coming from the canister to the intake manifold and the valve is located in that line and is electrically controlled. It's the only valve in the line and once you find it you may be able to close it off and see if it effects any change. I believe in your model it's in the engine compartment , but not positive.