I just replaced my spark plugs while changing resistor tips anyway. The car is my '89 190E 2.6. I used NGK copper-core plugs gapped at 0.032". The old ones were Bosch DCO Super plugs that my technician had purposefully gapped at 0.045".
What was he tweaking by putting them so far out of spec.? I ask because I may wish to do the same, as the car now runs smoother, but with less power.
Thank you for another tap into the knowledge base, Andrew Seidel.
89 190E 2.6
83 300TD Turbo