My 72 F100 Bump side with a 302 has a heating problem. It doesn't produce enough heat. The problem is that during cold weather, I cannot get much heat from the heater. Fan blows fine, lots of air. Heater core is brand new, with no restrictions. Thermostat is new - actually the second new one. Temp at the thermostat housing is 190 deg. Heater hoses are new, except for the bypass hose. If it is less than 40 deg., my entire 20 minute ride to work is cold. Any help is appreciated!!