Throwing this out to the group here as I'm stumped:
2001 L36 car (3800) automatic. Lot of mods including L67 and T5 swap. Post swap engine will not come off idle. Starts great, idles fine but will not rev. I've retained the original L36 PCM, throttle body, DBW accelerator pedal in the swap. HP Tuners shows 0% accelerator position when accelerator is moved, steady throughout pedal range of motion. Verified 12v at circuits with red arrows in the attached schematic, good grounds at circuits with black arrows. Good continuity on wires in pins 16 and 18 coming out to DBW pedal going to PCM. I believe the signal coming out if pins 16 and 18 DBW pedal are serial data but read ~2.5v with some flutter (I don't have an oscilloscope to read this). I've thrown a different DBW pedal and throttle body at it to troubleshoot, no change.
Any ideas?
Could an immobilizer issue cause this??

 

try pm to gorn and ask to have him look at thread. I am thinking it's the auto pcm. do you have access to manual pcm from new engine.