Hey, I'm kind of new to this forum and using a forum so sorry if I posted incorrectly.

I have a 1982 Trans Am, 305. It was running perfectly only over heating once in a while, but a couple months ago it developed a problem. At first it would just sputter and when you floored it, it wouldn't move. It would jerk around and i barley made it to the mall and back which was only down the street. I changed the spark plugs, wires, got a new cap and rotor, and a fuel filter and none of those fixed the problem.
I'm not really sure what to do now I don't want to keep buying parts I don't need. People have been telling me a new fuel pump or O2 sensor. I'm a full time student and I don't currently have a job so I can't keep buying stuff that won't fix it. Hopefully some one can help me out a little. I'll answer more questions if asked. Thank you!!!