Ok usually, when I push down on my gas, it doesn't accelerate very good like a Town Car, or any car should. I have to press it down pretty far to get it to start picking up speed at a very decent pace, and it usually quit going past 80 very good. Occasionly, it would fix itself and accelerate very nicely with no hesitation, but go back to being slow later on.

I recently got a well deserved oil change/filter and new air filter, they were both needing replacing badly, and my car started accelerating with no hesitation, except this time, it didn't go back to being very slow. It's better than it was, but I have noticed again, decreased performance. It's not accelerating as good as it was like when I first changed those things a week ago, though it is faster than before I did.

I'm wondering if there is something else that could be affecting the accelerating hesitation, because I know it's STILL not how it should be. Any parts I should have checked/replaced?

gaskets, exhaust could be clogged (catilitic converter). uhhh, not a mechanic but those are some problems.