My car is very jerky at low speeds, what is causing this?

I have a 2006 lexus IS 350. I got into minor car accident a few months ago where I drove over a dead deer carc. I needed to have some body work done to replace the front bumper and repair the under carriage. But now when I drive it, it doesn't seem very smooth at all. I feel every bump in the road, the car seems to lurch and jerk forward when i'm coming to a stop or accelerating from a stop. Does anyone know what is going on?