transmission problem

[mudbogz71]

hey guys newbie here, I have a 99 Chevy 5.3 z71 with a 6in suspension lift and a 3in body lift on some 37in tires. i had my transmission rebuilt about a year ago. have done little to no off-roading since (work and school have kept me extremely busy this semester) i haven't had any problems with the truck until yesterday in the morning. my truck felt like it was a little accelerated, and it didn't feel like it was shifting right.(living here in Houston TX we have had some weird weather, 40's then 80' and then 50's off and on) after work i drove it home and it wasnt shifting at all. the rpm went up to 5000 before i let go of the gas. not gonna try and blow up my engine here. if i popped it in 3rd it would shift after put it in regular drive. any insight, any little information would be greatly appreciated.

thanks guys

[gmtech4]

get it scanned