If your car is revving when it's not in gear, it's probably something else. Most likely an intake leak or a mad / dirty maf sensor.

Is it staying high when you start the car every time or just first time in the morning?

I remember when our OZ Rally was doing it, it would lock into 2nd gear to limp the car back to the dealership. So the rpms would go really high at times.

I know there were flashes that required for those years of cars. They were running too rich and killing the catalytic converter and the 2nd o2 sensor. If you have a bad o2 sensor that could cause some high idling as well.

I remember when the OZ was doing that I remember it idling high and being jerky to get into gear. So I wouldn't be surprised if the sensor fixes everything.

 

Excellent, thanks for your input.

The higher revving at idle, it happened the last two times I started the car and both times it was after leaving the car off for at least 12 hours.

I'm supposed to pick up the car tomorrow and I'll post the results here. I'm kinda leaning in the same direction as you and hoping that the new sensor fixes everything. If not I'll try your suggestions. Thanks again.

 

Got the car back last night with both sensors replaced. Problem seems to be gone now, and overall the car seems to run slightly smoother too.