And you have no "Check Engine" light? Is that right?

You might try to get the codes read, even without a Check Engine light, there may be pending codes that give you a hint of what is going on.

This can't be that hard, the PTCM knows the engine speed based on the Crank and Cam sensor signals. It has to be speeding up the engine because it is trying to compensate for SOMETHING.

I wonder if the temperature sensor is telling the PTCM that the motor is not warming up? That is, it is "high idling" because it thinks it's not warmed up yet.

This device would allow you to read codes AND see the readings the PTCM is getting from various sensors. I have one and it has helped from time to time (and is a fun toy to use when things are working right!)

UltraGauge OBDII Scan tool & Information Center