I've been having an issue where the vehicle has trouble starting after it's been sitting for 4 hours or more. It starts but then stalls right away. If I step on the gas pedal for a while, put it into gear, and drive for a couple of minutes, everything is fine and I have no issues starting it again... until it's been sitting for another 4 hours or so. I have a new starter, alternator, battery, negative battery cable, throttle body assembly, and fuel pump and hose, but the issue persists. Anyone know what the problem may be?