Start looking for vacuum leaks. For instance, my M103 has a small leak on the underside of the intake manifold. It is something I can live with, but it isn't much fun.

I replaced all of the small vacuum lines on my car as part of a broad campaign to replace all of the rubber parts. I used the small line available from Autozone, or just about anywhere, and that made a difference.

__________________
1986 300E - Ugly color, gorgeous heart.

Never let a German car sit still.

German cars don't leak. They mark their territory.