I would get a container of coolant flush and flush your engine. Be sure to follow the directions. Also, be sure to use ONLY distilled water and nothing else. Any other water can have impurities like calcium that will stick to the surfaces and cause flow restriction through the radiator. If after flushing the engine the temperature is still too high, I would take the radiator to a radiator shop and have them check it out. It might need a new core.