No power/car shuts off if I press the gas pedal

This car had a head gasket replaced and ran fine. About 6 months later I'm coming home from work and it started to shut off as I was driving. Now it will start and idle but will stall if I hit the throttle. I've replaced spark plugs and wires, mass air flow sensor, new air filter, new fuel pump (with everything included). Not sure what else to look at or change to make this car run. It seems like it's either starving for air or not getting gas. Any info on this would be great as I can't afford a mechanic.