Another thing to diagnose what is going on is to use an infrared laser pointer thermostat on the radiator or the water pump area while this is going on to see what the water temperature really is compared to the thermostat gauge in the car. I may be wrong on the locations to check the temperature; someone else may chime in to give better advise, but I would definitely use an infrared thermometer -- they're great for trouble shooting plugged radiators, or jacked up thermostats.
Best of luck!!!!!!!!!!!!!!
Mark
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