Why is my car over heating Pontiac grand Prix 2004

You could have simply been low on coolant when you pulled the hose - meaning there may have been a leak in the coolant system. Try doing a pressure test on it, as well as flushing the radiator to see if you get any flow through it. When you run low on coolant or have an obstruction in the core you tend to lose heat inside the passenger area. (The heater core is a mini radiator and works just like the big radiator.) Low coolant levels, bad water pump, bad thermostat, or obstructed heater core can all result in no heat to the cabin. Low coolant, bad water pump, obstructed radiator, blown head gasket, can all result in overheating.

Did you burp the air pocket(s) out of the cooling system with the bleeder valve?