DMCH stage 2 auto - 7K miles. Recently started diagnosing an intermittent hot stalling issue and a new issue popped up a few days ago. Started the car and as soon as I pressed the accel pedal, the idle shot to 2500 and stuck. Before this the car never did that and has always run well. Checked and lubed throttle cable, checked vac lines & electrical connections and all seems ok. When I unplugged the outer connection to the idle ECU the idle corrected to 750-780. Removed the ISM and it looks clean and "clicks" when shook. Car runs and drives with that plug disconnected.

Water pump was replaced by DMC before I took delivery (2022) so I assume thermistor and it's connection were checked/verified. Can the thermistor go bad that quickly/randomly? Is this a sign of a faulty idle ECU? Anyone have a spare idle ECU I can use for testing?
idle ECU.jpg