Just want to share some info: for the past couple days my MCS was shaking more than usual, when starting/stopping the engine.
At first, I thought about misfiring, bad gasoline, or some sort of ignition problem that would make the engine stumble.
Then I realized it was getting worse, so I opened the hood and tried to shake the engine by hand, immediately hearing a suspicious metal noise coming from the bottom. So... I lifted the car and... surprise surprise... the 4-bolt flange of the lower engine mount (on the engine block, next to the power steering pump) was completely loose, with 2 bolts missing and 2 about half way. I tightened these remaining two, putting some Loctite threadlocker red, just to be safe, and I'll be ordering the other two bolts asap.
I guess I can consider myself lucky for noticing before all 4 bolts were gone...

 

HATE bringing this dinosaur back to life, but i have the exact same issue. except i am not at all mechanically inclined. would this be a quick fix at the dealer? can you point me to parts you ordered?

 

^should have mentioned i have an r56, but my issue is exactly like what you had. same root cause maybe?