1994 Saturn SC1 Something wrong with the fuel system?

1994 Saturn SC1 Automatic

Okay, there are a couple things that are going on with my car right now. First of all, it starts up really rough. It putters a lot, and the RPM's usually go lower than 1000 like it wants to stall out. Sometimes it does stall out. However, if I apply a little bit of gas, it will prevent it from stalling. Usually black smoke comes out of the back when it starts that rough. Only temporarily though. I also experience hesitation while pressing on the accelerator pedal, but only when I first press on it. After that, it accelerates ok. Still, it doesn't have the power it used to. And finally, my car eats gas really quickly. It seems I'm using double the gas than I should be. I took it to a mechanic, and he said to replace the TPS sensor. So I did that, and I still have the problem. I've also replaced the fuel filter, and I had a tune up done in June. He also told me to clean something out when I replace the TPS sensor, but I forgot what that was. Maybe that's why I still have the problem? Another mechanic said that I may need to replace the fuel pump. But I travel about an hour and a half to and from college 4 days a week, so I don't make much money, because almost all of it goes to gas. So I just want to be sure that it is the fuel pump before I replace it. Hope you can help.