Progress updates...
Using the new ECU and making rough adjustments to the new TPS, my XT6 started without the superspeedway 5,000 RPM scream. I picked up a set of feeler gauges to test and fine tune the TPS, but I think I need a longer gauge set, so as of now I'm unable to test and adjust per the FSM. All I could do was tweak the TPS a bit, hand tighten the top screw, start the car and hope it's good. I get it to a point where idle is between 750 and 1,000 RPMs and throttle response is good. However... when I give it gas from the pedal (didn't try at the throttle), RPMs smoothly go up as expected for a few seconds, then the engine shuts down. My guess is that I need to fine tune the TPS ohm readings, per the FSM.
Any suggestions guys? Do I just need to drive the car and the ECU will learn?
Good news...
My original issue was high idle (1,500- 2,000RPMs) after a hot start. I have cured this gremlin! The engine was warmed up enough during my back and forth TPS adjustments, shutting the engine off and restarting several times. Not once did RPMs jump the way they did with hot starts.
I'm done for the day, made some progress but not finished.