2005 Pontiac grand am overheating replaced intake gasket checked hoses replaced thermostat what else could it be

find the bleed valve on coolant system and burp it. make sure you are using a good 50/50 mix of coolant.
maybe run a coolant system cleaner . maybe a clog?
if worst come to worst blow head gasket

you have a GM common problem and that is a bad intake manifold gasket. GM change the gaskets to plastic and they crank and leak causing over heating. here is a picture of one i took from a 2005 pon. bonneville with 74,000 miles on it

Have a cylinder leakage test or co2 test done. my prefered method is a leakage test as it checks heads, head gaskets, valves, rings all in one test.

Look in the valley by the t-stat , if there is coolant there it's the intake gasket. If not then replace the t-stat seal. one other place to check is the hoses going to the throttle body.

If you haven't replaced the thermostat yet, try that next.

Please see my tip at http://www.fixya.com/cars/r5929960-s_thermostat . These are generic instructions. If you get stuck or need specific instructions for your car, please get back to me with model, year and engine info.

did you bleed the air from the system? how do u know u don't have a leaking head gasket, have u had it checked with a gas analyzer?

check the radiator cap see if it hold the presure if not replace it

Thermostat, cooling fans, water pump, rad (not plugged wirth scale)

If its the 3.1L it could be your intake manifold gasket , the material used for the gasket does not react well with GM's Dex-Cool antifreeze. The leak may not be apparent at first, but I would pressure test the cooling system. If you look at the front of the motor by the belts , try to peek down at the intake manifold and check for slight seapage to an obvious leak.

If its either of the Quad-4's they were notorious for heads warping or cracking.

1 Inspect Cooling System Mix Coolant level low or flow is restricted. 2 Inspect Belt Incorrectly routed, adjusted, tensioned, missing, or worn water pump belt(s). 3 Inspect Oil Pan Gasket - Performance Ruptured, cracked or leaking radiator hose. 4 Inspect Radiator Cap Worn or damaged radiator cap 5 Inspect Thermostat Thermostat stuck closed 6 Inspect Fan Blade Broken, missing, or defective fan blade(s). 8 Inspect Water Pump Damaged, worn or leaking water pump. 9 Inspect Intake Manifold Plenum - Perform Leaking water pump gasket. 10 Inspect Cooling Fan Control Faulty cooling fan control or circuit. 11 Inspect Cooling Fan Switch - Radiator Faulty radiator cooling fan switch or circuit. 12 Inspect Engine Temperature Sensor Faulty engine temperature sensor or circuit. 13 Inspect Temperature Switch Damaged or faulty temperature switch or temperature switch circuit. 14 Inspect Fan Clutch Worn, loose or faulty fan clutch. 15 Inspect Ported Vacuum Switch Damaged, leaking, or faulty ported vacuum switch. 16 Inspect Radiator Obstructed radiator core or radiator cooling fins. 17 Inspect Head Gasket - Performance Head gasket leaking coolant into cylinders