When I start my car after sitting all night or for a few hours, it will start fine. But if I go some where, and try to start it back up after just a few minutes, it will not start. Some times priming it helps, or you just have to keep messing with it, Then when I get it started I either have to let it sit and see if it is going to die, and if that happens it is the same fight, but then it will make this loud bang followed by black smoke out of the tail pipe, and then a few more attempts and it will start. What could it be??