2001 Forester, 166K miles. I know, I know…head gasket. However, I have just done the head gasket repair and I still have some overheating problems. I did the head gasket myself, so there is some chance I screwed it up, but the car only overheats at 60 mph, not at 75 or 80, like it did before. I have found and replaced a blown fuse controlling the subfan. I have also replaced the thermostat and the coolant. Like I said before the problem only comes when I go 60, and disappears if I downshift to 4th, turn on the heater, or accelerate to 70 or better. I am at a loss. Thank you.
Have you done a pressure test on the coolant system?
Have the coolant tested to see if exhaust gases are getting into the coolant. If the test shows no trouble there then you may need to replace the radiator.