car won't stay running...help please

If it ran out of gas or was just ran low on fuel your fuel filter could be or is plugging up and when you shut the car off the pressure drops at the pump and crud fall's to the bottom of your filter, when you turn the key it starts then the filter plugs back up:glasses7: may be :coffee2: This could be easily checked, pop the hood and remove the air filter and when it dies look in the carb and see if fuel is pumping in the carb.