Ok so here goes Ive got a 2002 buick with a 4t65e trans with a no upshift problem the trans is stuck in 1st gear and wont shift out of first and into second until the trans is very warm if driven to 35-40 mph it will go into neutral where 3rd gear should be i replaced the valve body and spacer plate and installed new shift sols and a new pressure control sol i can here the shift sol'* clicking on and off when activated so I know they are working like
I said above it will start shifting correctly after the trans has been driven about 15 minutes, the fluid level is correct and the fluid is not burnt any thoughts?

Scanning the car for any codes would be helpful, use a good scanner for stored or pending codes.
Almost sounds like something in the valve body rebuild is not right.
What was the trans doing, acting like before you did the work?

I have a tech2 scaner thje car has no stored codesthe vale body i put in was from a gm dealer and i put 2 in thinking the same something was wrong with the first however ive got the same issue