overheating

I have a 2001 Malibu with 98.000 miles. My car is overheating after I drive for a short time the antifreeze is blowing out of the overflow and when I start it again it tells me low on coolant. We changed the thermostat, the intake gasket, the waterpump is working good, the heat gasket is not leeking- what could it be?????????

Have you tried to replace the Overflow Tank Cap? The seal can rot away, not allowing the tank to hold pressure, and causing an overflow.

Is your fan working? Turn the A/C on and the fan should start up. If it doesn't you need to verify the relays and fan connections. When your temp gauge gets to approx. 3/4 of the way, does the fan kick in? If not you probably need another sensor.