Thank you. Your comments and suggestions are sensible and reasonable. I, too, prefer to solve the problem at its root whenever possible instead of a quick fix. A good mechanic, as you described it, is also a good engineer. They are hard to find. Unfortunately, in my area, it also means that sending a car for dealer service does not guarantee that a good tech will be working on the car.
Luckily, the previous owner of my car loved it and babied it. I really like my car and have taken very good care of it. The car is very clean and I don't let any problem linger.
After reading you message, I feel better now about getting the vacuum leak checked out first.
'87 190E, 2.3-16