While Jeep did a lot of things well with the TJ, the engine mounts were not amongst them. If yours haven’t ripped apart yet, they will soon. There are a lot of good aftermarket solutions such as Brown Dog or M.O.R.E. heavy-duty rubber mounts or many polyurethane mounts. With six-cylinders there is little to no added vibration, but with the 2.5L four-cylinders there will be added vibration at idle and the poly mounts are worse than the rubber mounts are.