The temp guage has never deviated much from 1/4 off the peg even on the hottest, air-conditioned days.
I should clean the injectors anyway with the mileage I got. You mentioned EGR... is that controlled from the computer or mechanical? This is after all just a part throttle problem that goes away when you mash it. I believe EGR is supposed to only be "on" during part throttle. You might be on to something there, I will check. Would reducing the coolant temp via a thermostat change or new coolant mix be a good idea? I have my doubts it would have much effect on this car.