Checked the distributor cap and rotor yesterday, it appeared as though there might have been a bit more wear/corrosion on the number six wire .. I lightly sanded all the contacts in the cap and the brush on the rotor and put all back together. Driving to work today, engine got up to temp .. stop and go traffic .. smoooooooth idle! But, this could just be a fluke so I'll put the celebrations off for now and put some more miles down before calling it good. There is still an ever so slight stutter, but it's basically how the car has always run, certainly nothing like how it was. That slight stutter is hardly noticable and when it's absent you can't even tell the engine is running, this in drive too!

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1992 190e 2.6