96 Monte Carlo with the 3.1L v6, it idles quite high at start up, sometimes ~1200 all the way up to ~2000 and it won’t go down but will slowly climb. After warming up it will occasionally start at a good idle for a second or two then jump up and rise slowly. All intake sensors have been replaced/test and are good. Voltage test shows the correct voltage at the TPS. Gaskets have been replaced. Used smoke machine and found a terrible evap leak but with that patched up it acts the same, no other leaks found. The only remedy I have found is unplugging the IAC during the few moments it is idling correctly, leaving it disconnected and just riding with it in the same position. Could this be an issue with the ECU? I’ve found no wiring issues anywhere either.