whats wrong with my car?

For the past several months my car has been hesitating slightly when im just cruising down the road at around 50mph. Well, i finally got sick of it and figured that if i changed my spark plugs it might get rid of the problem. After changing the plugs however, i discovered a whole new problem. My car now has an extreme amount of hesitation and jumpiness when i am trying to accelerate at all. I have read some stuff in other forums about problems with the dpfe sensor and i was wondering if this was the problem. Also, why would the changing of spark plugs trigger such a drastic change in the way my car drives? Thanks for any help.

Try changing your plug wires and verify the gap on your plugs

Basically, just a bunch of tune up type stuff could help...a new coil comes to mind, as that helped mine, and a few other people with similar problems. The EGR, PCV valves, fuel filter even. How recently have those been changed?