I didn't ask, so I don't know if he did or not.
Fwiw, the fuel filter, fuel pressure regulator, and fuel pumps were replaced at 127,000 miles. I was chasing another problem by a different mechanic, and the problem all along was a bad spark plug wire.
I think my car really needs a priest or a rabbi.
What's strange is - why would the rhythmic, fluctuating idle only occur after the car has warmed up? I think this is the key to the problem. The car must be completely warmed up until it starts happening.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".