High Idle problem

[Bones192]

I have a 92 X that has an idle problem and it seems to occur after warmed up and possibly after a heavly load at low RPM. But it is erradic, so I have read the many threads on the topic and tried many of the suggestions. I have replaced the following: TPS, IAC, and the MAF. The RPM at first were hanging at about 1500-1800 RPM when I can to a stop after a few mile run. Now the RPMS are closer to 2200. If I turn the enigne off for a few seconds ,after the failure, and when restarted it returns to a normal idle. I think this would elminate any mechanical failure (vacuum leak, bad connection etc.) What should I consider before I send this thing to the dredded service shop? Any insight is greatly appreciated.

 

[Bones192]

Bump!

 

[TPLYNCH]

Thermostat/Temp Sensor? If the computer is reading an overheat condition, it will bump up the idle to try and cool the engine.....

 

[MrShorty]

Wouldn't hurt to run the EEC-IV self-tests to see if the computer can shed some light on the problem.

 

[Ozonkiller]

Does your tranny act a little wierd also? JrGaylor posted similar problems and found it to be the throttle position sensor.