Just last week I took pity on a poor 300E owner that couldn't afford the $676 plus labor for a new distributor. We pursued the problem and were able to fix the distributor. The next day I got a call from a fellow shop owner with the same conditions. I told him what we had done and he proceeded to fix his car.
This is fairly rare but the problem involved was one I had seen a few times. We had always just replaced the device in the past. The problem involved has the symptoms of vastly different mixtures at different air flow rates. Testing showed way too high differential pressure.
Replacing the distributor is fairly simple but the getting the adjustment right will take at least the tools mentioned in my DIY article.
Bosch Master, ASE Master, L1
33 years MB technician