1992 Mercury Marquis Slipping out of OD

My transmission slips out of OD or refuses to down shift to passing gear when accelerating to highway speeds. Also much shuddering at the same time. Lower gears are fine. Same problem in all temps. Better out of OD position but not much. It seems like the Torque convertor is slipping. Also there is a vibration fromthe right side of the vehicle at highway speeds. Don't know if it is related. Cruise does no function properly either. ANy help would be appreciated.