I have 93 with M104 (3.2L). A few years ago, same thing happen to my car, not over heat but run a little hotter than it should be. Without AC and traffic, a little over 100 C. With AC and traffic, a little over 105-110 C. If the car moving, it seemed to be OK. I know it's not water pump or thermostat cause did replace them a year ago. Thought it's a fan clutch but before I could have time to replace it, heard the noise and check it. Turn out to be the bearing of fan clutch bracket gave up. Change the bracket and have no problem after that ( now about 90 without AC). hope it help.