I have a 2001 Tahoe 4x4 having an issue between 2nd and 3rd gears. If I drive at 1500-1800 rpm it shifts just fine no slipping. However if I go above 2k rpm sometimes it will not shift. I can rev it up and still feel no slippage, just won't go into 3rd. Do you think it's time for a rebuild or could it be electrical or solenoid?

 

Could be the throttle position sensor.

 

Just concerned that I have no engine light, nor do I get any with the scanner.