Just drove from Detroit to Toronto, climate control was set to 70 with outside temp in mid 50's the vents were blowing relatively cold air. The air was getting warm if I cranked it up to 78. UltraGauge was showing engine temps to be 94 on the highway. In the city I usually run from 97-104 and did not notice the truck being cold Even in winter. Any idea why I don't have enough heat?

 

Low coolant could cause that, along with clogged heater core. You could feel heater pipes in/out, if one is way colder, flow could be restricted. It is possible to flush the heater core in both directions. With 219F being reached, might be a good time to flush the main radiator as well....