Overheating and questions thermal sensors

You can check your radiator for proper cooling with a cheap IR gun from HF. Take a series of reading from top to bottom in a 3 in grid pattern once the engine is up to temperature. Clogs in the radiator will show up as cold spots and usually show up in the center of radiator in front of the fan clutch. You should read about 200 degrees at the inlet on top and 30-50 degrees cooler at the out let on the bottom if your radiator is cooling properly. you can also back flush with a garden hose at the outlet with the thermostat removed and use a pan under the lower hose and see how much sediment comes out. Also the temp sensor in the left head can go bad and give a false reading, shoot the sensor and the T-stat housing with the IR gun and compare those readings with your gauge readings. Let us know how you make out.