I dont see an aftermarket header causing too much heat in the engine bay. If you replaced the iat sensor and you still have a cel you should look into the wiring.

As for your overheating check your coolant level make sure its full and not low. Check you cooling fan and make sure thats coming on. If the coolant hasnt been flushed try that and change the thermostat.

 

Thanks for all the advice so far, im replacing the thermostat today and I'll flush the coolant as well, I'll keep you all posted

 

changed the thermostat and flushed the radiator, the gauge isnt saying its running hot anymore, thanks guys, but i still have my check engine light on with the same code PO113 air intake tempature is to high, the sensor (int sensor) has been replaced, any idea on how to fix this problem? or what is really wrong with my car?

 

Check the wiring from the iat sensor back to the ecu, you might have a broken wire.