Whilst I am not an expert on MB injectors, I suspect you may have an injector hanging up.
You have rulled out the head with all the work you have done, but I expect if your car was using oil before you started, that the injectors need servicing.
If you were here, I would suggest you memove the injectors, and take them to a Bosch injector shop for servicing.
The problem with miss's, is the fact that there are so many factors that could come into play.
A simple suggestion, which may assist, is to run the car on a very dark night, with the hood open. This way if you have HT voltage tracking down say a plug lead, or the distributor cap, you will be able to see it. Try removing the distributor cap cleaning it with a rag with gasoline on it, and carefully look for scrathes or hairline cracks both inside and out. Pull the HT leads one at a time, inspect the terminal that goes from the HT lead into the cap, and clean both metal parts, of any rust or mould you see there.
With luck you can find that it is something simple.
Let me know if I can be of more help.