I have a 2002 Chevy Cavalier with 95,000 miles. Due to me being in the Marine Corps, I haven't been able to drive it much in the last 3 years thanks to deployments. But one day i started it up and it started blowing out black smoke, idling rough, and there is a strong smell of fuel in the car. When I drive it around base it drives normal but the fuel mileage is next to nothing..Any assistance would be greatly appreciated..

If you have had the same gas in there the whole time it has gone bad fuel goes bad pretty quickly when you get deployed you should add fuel satbilizer or have sombody start it for you.

The black smoke is the result of a very rich mixture. After sitting for so long something is definately gummed up, especially if it's been the same fuel in the tank for 3 years. I would first check the injectors to see if one or more are leaking. How's the fuel pressure?