[mustardjohn]

I had a '94 T-Bird that did that. It was something relatively inexpensive. Not the transmission proper but some electronic part on the outside of the trans. Mine would not do it until the car got hot say after 30-40 miles or so. That made it difficult to trouble shoot. Would never do it when I would take to a repair shop. Had to be hot. It was a real problem like it would jump out of gear then when you let off the gas the rpms would come down and it would reingage. Hard to trust a car like that when you want to pass on a two lane road.