I gotta agree with everyone that responded so far. When my tranny lost reverse it acted like I had a high stall convertor at first. It took lots of pedal before it would start to move. Then after a few times backing up I had nothing at all. If you have nothing and then it's working fine again it sounds like the "touchy adjustment" is out of adjustment. If you're definitely swapping trannys and the new trans has the same problem, then linkage adjustment is your issue.
