Black smoke out of tailpipe

Black smoke comes out of tailpipe, runs but wont stay running what could this be? When I back up it stalls, and it is a chevy and its white my wires have not been replaced in a long time but the spark plugs have could this be my fuel pump I just had it replaced 5 years ago what do you think please reply with the bestest possible answer high mileage please reply with the good answer and I drive it alot with my daughter and every time I start it it has black smoke coming out of the back and it smells like gas alot and stuff and recently black soot has been coming out of the tailpipe too it looks like oil and aloso please give me a good answer and or should I get rid of this van yes or no it stinks badly I have already fixed my fuel pump and I think something is wrong and it is clogged maybe it is my catillatic converter spark plugs have been changed recently and it stalls when I back up and black smoke has been coming out of tailpipe for about a year when I go from stopped at a light to going forward, what could be clogged in there and why is black soot coming out of the tailpipe at the back of the van thank you