Found a pretty detailed thread that might address your problem. It takes you through a few steps to diagnose what type of a vacuum problem you have ......my uneducated guess as to the root of your problem. Unfortunately, it's an old thread and not easy to find. PM me and I'll see if I can direct you to the thread. Full disclosure, 1 wife, 3 daughters, they love driving my Benzes, but think a good paint job is something for your nails. You are brave to venture forth with your 280,