This is pretty common on Dodge - Jeep - Chrysler vehicles. The Fuel Pump has a check valve that keeps up the Fuel pressure when the engine is shut down. This way when you crank the engine, the Fuel Pressure is ready for the Injectors. When the pressure holding check valve becomes worn out, it may take 10 or more seconds to build up pressure in the fuel rail to be useful for the injectors. The system will bleed down a little if you stop to get a bite to eat, but over night the system will bleed all the way down, which explains your puzzling sympton. Eventually the pump will go out all together. I would not vacation in your car like this. happy 4th!