You know, I recall that I had a bad coil wire and experienced a lack of power and backfiring.
I just couldn't believe that a simple coil wire could cause that big of a problem.
I left it with a local independent Mercedes mechanic for a couple of days. He gave up and took the car to the nearest Mercedes dealer himself, and paid for the diagnostic work.
He paid the $90 himself, and sheepishly admitted that it was a bad coil wire.
He was looking for something difficult and missed one of the first things he should've checked....
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".