Randomly shutting off while driving

While driving at times it shuts off. Not all the time it does this. Sometimes it will sputter slightly then shut off, on long drives it will shut off if I let it set for a few seconds it will start up and then continue to keep starting and stopping. Other times It will start up after being shut off for a few seconds and drive fine. Sometimes while sitting idling after being driven it will slightly sputter and then shut off. It has ran out of gas before. I do not know if this may have damaged the fuel pump because at times I hear a muffling banging pumping like noise coming from the rear left. But then it could be the exhaust system or catalytic converter. please help!