2000 subaru legacy outback - Overheating

Have a 2000 subaru outback 2.5l, automatic, with about 245k, I replaced the thermostat,water pump, the radiator and the car is still overheating. both fans are working. no leaking coolant. Maybe this may help or related- over heats mostly when driving on the highway. But if a shift the gear to neutral and coast for a minute the shift back to drive the temperature gauge goes down. Any idea whats wrong, running out money fixing the car, but love it driving it in the snow.

Is the radiator cap new?

You could have the coolant temp sensor tested, but I don’t think that’s the problem.

Have the car tested for a leaking head gasket. It’s a common problem with this car, especially at 245K miles.

Overheating at high speed = leaking head gasket.