I was desperately grasping at straws, and to no avail. The OE pump did not change a thing. I am completely stupefied by this car.

All I can hope for is that one of the ‘Super Techs’ here can pipe in on this exasperating situation. There is no substitute for experience. Someone that has witnessed the idiosyncrasies of dozens or even hundreds of these cars may have an idea. Perhaps one of their customers has had a similar problem; perhaps it is an early sign of greater problems yet to come, such as a head gasket in the early stages of failure? I don’t know.

Additional information: This does not seem to be a problem with cooling capacity per se. For example, when the gauge was reading about 98, I checked the temperature of the *hot* side of the thermostat housing, the infrared thermometer read 99 degrees. The (cooled) water return pipe going from the bottom of the radiator to the thermostat housing reads between 60-65 degrees; so the radiator is cooling the coolant. This would seem to indicate that the thermostat is not opening properly, but I’ve now had THREE different thermostats in the car. What are the odds of 3 bad thermostats in a row? Rather astronomical. If only I had such ‘luck’ with those odds consistently, I’d play the lottery!

Thanks Again Everyone!
RTH