I have an 01 2dr 4x4 automatic. I replaced my post cat o2 sensor this mourning and it started and drove just fine. I unplugged the battery to get the code to clear, which it did, but now as soon as I try to put it into gear the rpms drop and it dies. Any help would be appreciated.

 

I would check over any and all work that you performed. The replacement of that O2 sensor should have nothing to do with the operation of the motor. The code would have eventually cleared on its own.

 

You IAC valve is very very close to dying, but the computer progressive learning has kept the vehicle running....now, with default expectancies, the IAC can't keep the idle correct?

Just a thought...also could be any other sensor along those lines that can fail as the PCM learns, but with a reset the PCM detects fail?