I have an 01 2500 4x4, auto. I changed my thermostat about 9 months ago due to the fact that mine was stuck open. Wouldn't get warm in winter, had to stick a piece of cardboard in front of the radiator to get it warm. I installed a new t-stat and the temp stays between 220 and 190, is this right? When I get up to around 80mph, the temp rises. I'm not sure what the problem could be. Thanks.