Car stalls and "jumps"

What is your question?

I just bought my 95 Chrysler Concorde not too long ago.. The car had been sitting for some time before I got it. After I put gas in it for the first time, it started to "jump" going down the road. Then it got to where it wouldn't start until I popped the hood. The other day it stalled on me when the temp outside was 83 (the first really warm day since I got it) and has been running fine this morning. I'm really confused as to what could be wrong with the car.. I've replaced the spark plugs, wires, and ignition coil. It's still "jumping".. What could possibly be wrong? Someone told me it could be the fuel pump or the fuel filter.. Please help, I'm desperate..