You know, I just had this fixed on my 300D! I had the same problem. First it was the engine mounts, I also had the "rac" adjusted, it was good for about a year. In the hot weather, or after demanding drives, she started shaking again. Another pump adjustment later, all gone! A few months later, same problem. No more adjustment left in the "rac." So, it turns to be the adjustment mechanism (if I can remember right). A new screw (or whatever it was, I really have to check) and its fixed! This seems common. Sorry to be so vague, but I just had a load of stuff done, its hard to remember everything!