Why does my car shake and jerk when stopped?

What is your question?

I have a 2006 Mitsubishi galant. I recently just got it back from getting it fixed at a shop. It's a 4 cylinder and 2 cylinders weren't compressing. Mechanic fixed that problem. But now it shakes when I start to slow down and jerks when it's stopped and parked What seems to make the problem better or worse? When it's stopped How long have you had this problem? 3 days