I was thinking about the motor mounts as these also cause similar problems on Porsche’s. I was hoping the seats were just showing there age. One thing I found out is I always do my own engine work, but I though to say time I would take my head into the local shop to have it resurfaced, as it was warped 8. thousands of an inch. What the local shop did was to remove 20. thousands of an inch. What would be the maximum that the head could be resurfaced?