1995 olds aurora not shifting into overdrive, intermittent issue
A lot of automatics will not shift into overdrive until the engine has reached operating temperature to control cold engine emmissions. If the lockout is happening inappropriately, have a transmission technician scan the computer to see if any codes are set and scan the transmission fluid temperature thermistor to see if it is reading appropriately. Also he can run a scan while the car is operating to see if the computer is commanding overdrive and the event is not occuring.
Get back to us with what you or mechanic finds.