I change water pump an thermostat and when on xprsswy car runs extremly cold what could be the problem ?

i change water pump an thermostat on a 97 sunfire 2.2 and when on xprsswy car runs extremly cold an i lose all heat what could be the problem ?|||was the thermostat the correct one for your engine?|||You probably have an air lock in the cooling system and it is not full of coolant. It could be that the thermostat is stuck a little open or not seated correctly or backwards, but I rather suspect you need more coolant in your system. Park the car with the nose a little uphill and after it cools, check the coolant level.