Car running hot somtimes 2000 masda
Have you checked coolant level in the (cold) radiator & reservoir tank?
Is the thermostat more than 10 years old? If so replace 'stat and radiator cap.
Use only OEM parts! Many aftermarket 'stats are junk.
That’s all we get? No model, no mileage, no history, no description of what’s been checked so far? No description of under what conditions it heats up?
C’mon, give us something to work with.