I have a 2003 avalanche z71 half ton.

when driving it seams to start in 2nd gear. Will not shift to third unless I speed up to about 4500rpm then let off to about 1000rpm. Will not go into 4th. Also does not seam to have any engine braking. I have changed shift solenoids. No difference. Then I changed valve body. No help. There was no code when it first happened then after a short test drive (15min) I had a transmission hot warning come up. Stopped and it cooled off quick and I had a check engine light. Then that went away just as I got the scanner.so no codes currently