You've replaced everything I was going to suggest.

I'm kind of stabbing in the dark, but did you replace the spark plug resistor boots?

Are you sure they are fully pressed on tightly?

What spark plugs are you using? You should be using plain old copper-core non-resistor Bosch or Beru spark plugs.

The resistance in these cars is in the spark plug end (or boot), so if you have installed resistor plugs, even platinum plugs, you have doubled the resistance.

Also, what about the mass air meters? Your car has two of them, and they can cause strange things to happen when one (or both) are going bad.

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".