In response to JimF, the car seems to idle smoothly in most instances, other than when the car stalls, obviously. I thought that it might be a plugged fuel filter, but that was just replaced. I believe that I am runnning 50/50 in the radiator with Mercedes red coolant, perhaps a bit more water since I usually just top off with water when low in the reservoir. The aux fans do kick on when the car goes over 100 C. I'm just wondering what the normal operating temperature range is for this vehicle, because maybe the temps I am seeing are not excessive.