Temp is normal but the air is warm when I stop & cold when I start driving again

Make sure there is not any air in the system and coolant level is full.

Sounds like thermostat has gone out.

Try this test, drive the truck with the heat on for 20 minutes, cut it off and let it sit for 30 minutes or so. When you raise the hood if the upper radiator hose is collapsed that is why it isn't heating. The cause should be that the overflow tube and the overflow cap are clogged and the radiator cap is defective. If the upper hose isn't new replace it. Clean or replace the tube and overflow cap.