1999 Pontiac Grand Am Engine Missfiring?

Hopefully you understand my problem. While I am driving, my car will run fine. More often now though, when I am driving and go to accelerate my car feels like it is missfiring. I think you would say missfiring. It feels like the front of my car is trying to tug me up the hill. Just recently, it got worse in that I could barely make it up the steep hills on the highway. My husband put a new fuel filter in and my car does run better. It doesn't tug near as much, but it still will do it when I am trying to accelerate going up a hill. The fuel filter he replaced was on the rear of the car. I wanted to know if there was another fuel filter on the front of the car or not? I was told some cars have that. If not that then what else could it be? I do need to replace the fuel pump, I know that. If you could help, that would be great.