My car was shaking up a storm at idle, but I couldn't really find much in the way of a leak that might cause it. It seemed that there might have been a very slight leak at the intake manifold, so I replaced the gasket (and no, I didn't drain the coolant like the Bentley manual said!). It was a pretty easy job, especially since I already wanted to clean the TB and the flame trap.

As it turns out, the intake manifold gasket wasn't so much leaking as it was totally distorted. It was actually distorted inwards so that it would have been blocking the intake valve pretty significantly! So that's a lesson for you. Just because it might not be leaking to the exterior doesn't mean the gasket is still good.

Now it runs nice and smooth, and life is good.

One question: is it a good idea to re-tighten the manifold nuts after a few hundred miles? The Bentley gave no torque rec, so I just did it "nice and tight."