Pesky High Idle problem on 1992 Grand Caravan 3.3L

Hello, On my 92 Grand Caravan 3.3 I have a high idle problem that consistently trips the Code 25 (IAC circuitry). Here is what I have
checked and replaced. Idle Air Conntrol Motor Swapped out another ECM from another Caravan Cleaned throtle body area and replaced TBI gasket. No known vacuum leaks or other gasket leaks No other codes found The code 25 immediately sets itself even after I disconnect the battery for an extended period. I even disconnected the PCM and reconnected. It will show the code before I ever start the vehicle again. It sets itself when key is in on position and checks voltage. Resistance tests appear normal. For those who know a ton more than me: What would be your next steps if you were in my shoes? Thanks
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