Under hard acceleration between first 2 gears then I let up right after the truck gets into 3rd gear like about 30 mph and just want to idle at that speed, Trans drops back down to 2nd and revs the rpms up then it will aventually shift back into third , Only happens under this condition. When I accelerate normal and hold the speed at 30 it doesn't down shift. Is this a computer problem or is this the trans problem that everyone is talking about. I only have about 46000 miles on my truck and still under warranty 7yrs 80000 miles.

 

sounds like the shuttle shift

 

It may be the governor solenoid/transducer.