Thermostat: replaced. Temp sensor: replaced. Radiator: fairly new NOT losing water.
Note, sometimes the temp guage goes wild up and wild down, while engine stays the same temp. (i take it thats a short)
But why does this car almost overheat at random times? (it does it after one hour highway driving)
What are the symptoms? You say the temp gauge sometimes fluctuates whole the engine is not overheating, so obviously you have some indication of engine temp besides the gauge. Is coolant boiling out of the overflow tank?
Also, what do you mean by “random times”? You said it does this after one hour of highway driving, which sounds like a recurring event, not random.
First thing I’d do is check for air trapped in the cooling system.
Are the electrical fans working correctly?