1996 Cadillac SLS Transmission failing to shift

Started on a warm day between San Diego and Phoenix. Great touring car wouldn't get out of second gear. Nothing above 45 MPH. No "safe mode" reported on dash. Traction control light on and anti-lock light on dash. No SES. Pulled over cooled off, not that it was hot, but I thought it would help, it did, no problem drove 65 more miles home. Lights on dash came back. Next time in car, no shifting gears. If the car sets for a while, the traction control and anti-lock go away, short driving distance, once backing out of drive way and once after about 30 minutes no similaries.