Transmission Trouble

I have a 1999 Chevrolet Tahoe 4x4. The Transmission seems to hunt for gears, upshift and downshift repeadily around 45 or 50mph. It also just shift erradicly sometimes and the transmission is 5 or 6 months old, I just had it rebuilt and it couldnt have more than 9,000 miles on it. I have taken it to the shop that rebuilt it twice and they told me that the problem was an engine miss and then I took it to my mechanic who told me there was nothing wrong with the engine. I dont know what to do now, can yall please help? Thanks
Sonny

Is the MIL light on ? Check for OBDII codes in the computer in any case. Some tranny codes don't put MIL on.

engine Malfuntion Indicator Light.

If you tap the brake just enough to make your brake lights come on (but not enough to slow you down) and the problem goes away, then the problem is with the TCC locking up. This can either be a valve body issue or the torque converter itself.

//2000CAYukon

The MIL light hasnt come on and my mechanic has run the scanner on it twice and it hasnt shown any codes, so I dont know what is going on with it, when you say tap the brake pedal lightly do u mean while i am also pressing on the gas? Thanks yall

when you say tap the brake pedal lightly do u mean while i am also pressing on the gas? Thanks yall

Yes. Pressing the brake causes the TCC to unlock so if your problem is with the TCC locking up, pressing the brake will force it to unlock.

//2000CAYukon