Original plugs and wires? Doesn't seem likely, but if that's so, you got your nickle's worth on those, and getting a fresh set would be a good idea. It sounds as though a regular maintenance program was never followed on this car, so I would begin that now. That means plugs, wires, cap & rotor, regulator brushes, all filters, all fluids, all vacuum lines. At least then, any further driveability issues can more readily be diagnosed and pinpointed. You may have needed EHA, O2, duty cycle adjustments and all the rest, but it sure seems like your tech came at it backwards.

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1988 California version 260E (W124)
Anthracite Grey/Palomino
Owned since new and still going strong and smooth
MBCA member

Past Mercedes-Benz:
1986 190E Baby Benz
1967 230 Inherited from mom when she downsized
1959 220S Introduced me to the joys of keepin' 'em goin'

There are only 10 kinds of people in the world--those who understand binary and those who don't