I want to start by saying thanks for all help. I have a 95 Deville 4.9 that recently ran hot, I have changed the thermostat, bypassed the heater core, and had radiator professionally cleaned. temp still rising fast after temp hits about 80. I was told it could be a bad temp switch. but I have driven the car. temp hits as high as 250 but drops down to as low as 223 but seems to run fine. what could be the source of my problems. ps. once temp hit the 250 mark I parked it, I have never tried to drive it with it that high.