So my heat sucks. If I turn the heater off the car will warm up at idle. If I turn the heat on the a/c fan turns on and brings the temp gauge down to cold and no heat. If I drive the car the heat gauge goes down to cold and again now heat. I've bleed the system, twice. I'm truly stuck and could use some sort of a direction to go next. Figured I the thermostat was stuck open it wouldn't even heat up at idle. Any ideas?

 

Thermostat sounds most likely if you lose heat when driving and gain heat when sitting still. In the opposite case it'd be air in the system.