It does sound like your vibration/shudder is related to a slight change in the driveline angles due to forces involved with hard acceleration. So, either your differential is moving too much or your engine/transmission is moving too much. I think you are on the right track, but it might end up being something other than the trans mount. Although the trans mount is one good possibility, you also should look at the rear subframe mounts and differential mounts (if 202 has them, I don't know). Also, in combination with the trans mount, the engine mounts play a role in supporting the engine-trans angle.