there is something wrong with my transmission. when driving down the road in 3rd gear (od off) between 35-50 mph and trying to maintain speed the trans acts like it wants to down shift but never does. if i press down the pedal ity will downshift and do down the road. in overdrive it does the same thing only it is between 45-65 mph. i have taken it to my transmission shop who said the transmission is fine. any clues?

 

Sounds like the torque converter is locked up. Perfectly normal.

 

BigBlue! I think you hit the nail on the head.