You aren't going to like this. A fuel distributor can cause just about any set of symtoms you can imagine that could be caused by fuel: single or multiple cylinder misfires, low or high speed hesitations, misfires, low power, high fuel consumption, dieseling, rich conditions, lean conditions and special cases of both.
The only way it can be fully diagnosed is with complete fuel pressure testing and differential flow analysis. Very few shops have the differential flow equiptment (including dealers - you are probably more likely to find this equiptment at a Bosch Service Center as it was required tooling). Fair diagnosis can be done with a good engine analyser doing a cylinder balance test with hydrocarbons. The concept here is that a good analyser will have a program where each cylinder has its ignition shorted for an exact amount of time and the engine speed reduction and increase in unburned hydrocarbon (gas) for each cylinder is noted/graphed. The amount of unburned HC should be the same from cylinder to cyl. Increases and decreases are noted.
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician
[This message has been edited by stevebfl (edited 04-10-2000).]