Cooling System Problem

1994 Grand Prix 3.1

I am having an issue with my cooling system. There is a leak in the radiator fluid somewhere, i can't tell where. I can't see anything on top and its not leaking out the bottom. When the fluid is low the temp goes way up and the heater blows out cold air. If I put the car in neutral and I apply pressure to the gas at about 2000 rpm, the temp drops back to 190* and hot air comes out. I have had several different mechanics look at it and I get different opinions. I have heard the head gasket, water pump, sensor and radiator. Has anyone had anything like this? Or does anyone have anything that could rule out one of the above? Thanks!!

The only way to know is to pressure test the cooling system. You have a cooant leak, which is allowing air into the cooling system which is causing your high temp and no heat issues. Common problems include the water pump (it will leak from the "weep hole" in the casting and get flung around), intake gaskets(they will leak into the engine, not on the ground), or a blown head gasket (sweet smell and steam from exhaust).