car keeps cutting off; won't start back right up;

driving at normal speed or stopped at a light, car cuts off; changed fuel filter and checked fuel pmup. Pumpp is working. Once it cuts off and I turn the key back on, it keeps turning over but it's like its not getting an electrical connection. Had to have it towed twice in less than 24 hours! All original parts still on the car except heater. Car just sitting now, don't know what to do. Had it since 2006 and a tneup once