It sounds like the transmission may be in a limp mode due to electronic control of the transmission being impaired in some way. I've had a fairly similar set of symptoms occur on my 95 sr a few times. It was an electrical cause each time in my case. A couple times it happened after doing some work on the center gauge cluster. At some point a short occurred and blew a fuse. Some of the electronic control functions for the transmission must have been on this fuse circuit. Transmission wouldn't go into overdrive. I believe I was also lacking 1st gear. The 3rd time a stick popped up between the transmission and floor pan and tore a few solenoid wires loose on the wiring harness.