Long story short, rebuilt trans and have had major issues.

Finally believed I found the problem and reassembled it today for the tenth time and now it shows a P0731 code and doesn't move.

Any guesses? All are welcome.

I've previously done the
-solenoid ohm - all good
-changed lead frame, harness (which the new one ended up being faulty), pcm (which was the original culprit after the rebuild) 2 different filters, clutch and steels rebuild kit with seals
-Rebuilt valve body with sonnex kit
-Had torque converter rebuilt professionally

Today I pulled the entire thing out again and tore it down. Found discrepancies between 2 manuals I've been using and noticed the B (low/Rev) clutch was too tight due to one manual recommending a thicker pressure plate. Swapped for the other manuals recommend plate thickness. And now the code. This truck hasn't moved since the rebuild.

Please, if anyone has any suggestions, I'm all ears!

 

How about the EPC solenoid? And did you put the valve body and check ***** back?
What was it doing to start with?