Based on all of the advice on the forum, I replaced my front motor mount last week (1999 with 90K miles) and here is what I found:
As you can see, the solid rubber portions of the mount are cracked. The cracks go all the way through. There was really nothing holding the motor in place, it was just kind of rattling around in the mount. I never heard or noticed anything, the car drove and sounded fine.
If you have an older Boxster, you might want to check your mount.
Threaded Mode
