I moved to Ny from Ga a month ago and as soon as I got here my heater took a crap. It seems to only heat when I accelerate. I changed the heater core , there is coolant in the reservoir and both tubes that lead to the core are hot. I do have a coolant leak but I think it is the flange and had the leak for over a year now so I don’t think that is the problem. I make sure there is always coolant in the car and can’t figure out what it could be. I have read numerous posts and well I hear it could be thermostat, water pump , head gasket among other things. I really can’t afford to spend thousands to get this fixed so I am looking for somebody that had a same situation and fixed it. Thanks