1998 Ford E-Series Van Not Starting

OK, so here its the rundown. I was having bad fuel problems, I would press the gas pedal and I would get no response and then the van decided it would only go 10 mph at full throttle. I had the fuel pump, fuel filter, Gas tank cleaned out and probably a few different sensors changed as well as a new computer installed. It ran fine for a few weeks. Now what is happening is it is having trouble starting, but only when the engine is hot. When I wake up in the morning an start it up, it fires right up. When I get finished driving and park it, turn the ignition off and try to restart it, It will Shake like crazy and blow black smoke out of the exhaus or it wont turn over at all. If you let it sit for about 3-5 hours it will start right back up. This is my work truck and it is driving me absolutley insane.