This happens AFTER my car is warmed up. It gradually comes in more and more as it warms up to operating temp. There is a sound that just sounds like putting or backfiring. Its completely random and the noise isnt in any pattern. You can mainly hear it through the exhaust, but when it makes this noise the whole engine shakes. My left side motor mount is broken so that might be why the engine shakes a little more, but still I know it probably shouldnt be making this noise at all. Anybody ever have this before?