How full is your gas tank when it's doing that, and how many miles does the car have? My car was having trouble getting up to speed, and it would "jerk" sometimes when I would give it gas. It only happened below 1/4 tank, then only below 1/2 tank. At this point I took it in, and although there was no Check Engine Light, there was a code in the computer. It turned out that I needed a new fuel pump. BTW, I drive a '99 Contour V6 Auto, and this happened around 35-40k miles.
