When I first bought my car six months ago it was missing, kind of a shaking feeling, I found the problem to be the spark plug wires. The dealership said it was partly because of a dirty throttle body, but I dont know if this was just bs or what. So my guess would have to be spark plugs, spark plug wires, or throttle boy.
You can check you plug wires for little white marks on them from arking, this is a sign of bad wires. But mine didn't have these and it was the problem. You can check the plugs to see if they need to be replaced. I really dont know about the throttle body though.