FWIW, disconnecting the battery erases the codes. So in reality, the "problem" did not go away, only the history of it. Also note that some problems must persist for some time before the code and the CE light come on, while other problems are posted immediately.

Check the output of the O2 sensor, to see if the mixture is detected as too rich or too lean, then continue diagnosing from there.

Make sure the throttle position switch is correctly adjusted, as it tells the ECU when the IAC should be active. If you adjust the throttle stop don't forget to readjust the TPS. It's possible (but unlikely) the IAC is faulty, but that would not cause the trouble codes you are seeing.

Also carefully check the accordion hose between the AMM and the throttle body. It rubs against the body and eventually wears a hole in it. You might have to remove it from the vehicle to check it thoroughly. If you can borrow another AMM you might want to swap it in on spec and drive with it for a while.