5.9l 4wd, 2000 Ram 1500. I have changed the water pump, thermostat, and flushed the system but the engine is still overheating. Intermittent heat in the cab but I can actually hear the coolant moving through the heater core. I am stumped!

To me it sounds like you have an internal leak of some sort, where the cooling system isnt building enough pressure to properly cool but still able to circulate. Does your truck smoke when it runs. If it's white smoke this would indicate your burning coolant. Try checking your oil. If it has a milky color then you have some antifreeze in your oil.

No smoke, no indication of oil in antifreeze or vica versa. I am not loosing coolant or at least not a significant amount.

Is the raditor cap good? It may not let the system build up enough pressure.