My truck trans. round 2!

Did you replace the PRESSURE SENSOR and PRESSURE SOLENOID in the GOVERNOR when you rebuilt the transmission?

My truck wouldn't shift like it should when the transmission got hot (normal temperature). I ended up replacing those two parts and I had no trouble after that. The PRESSURE SOLENOID is very prone to get dirt hung up inside it and will cause this. If you notice the PRESSURE SOLENOID has a very fine screen in the attempt to keep dirt out. My truck did exactly what you are describing in both paragraphs that you posted.