I have struggled with three different MB independents that struggled mightily with regular diagnostic work on my car. All three employed the "throw parts at it until it's fixed" method of repair.
I took Alon's advice and went to Mr. MB Motors in Encino and have finally found the right mechanic for my car.
What's more - he's incredibley reasonable. His hourly labor rate is $60 / hour. Heck, Pep Boys charges $60 / hour.
It's 51 miles from Diamond Bar to his shop according to mapquest, but it is worth the drive.
Bobby, you really should go see Enrique in Encino - you won't regret it.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".