car over heats heater blows cold air

I had very similar problem and mine turned out to be the head gasket, which is common among these engines 2.2L. Also, another possibility is that there is still air in the line. If you will follow the hose that comes up from the thermostat and then goes across the engine, NOT to the radiator, once the hose changes from rubber to metal, there is a bleeder screw there to be able to make sure that you get the air out. I hope that this is all your problem is as changing the head gasket was just a major pain in my rear.