Ran into this before but cant remember what I found the cause to be
01 truck ECU, command 2000 rpm idle and timing goes up trying to raise but IAC count does not. Command 0 rpm idle timing goes to min trying to lower but IAC doesnt respond
TPS does respond with pedal, no ETC flag in system menu
It will raise IAC counts upon startup and once startup airflow decays to 0, IAC count will stays the same no matter what desired idle is if its higher or lower??