Well, I've searched the site for hours and still have not found anythind that relates directly to my problem. I did find a lot of posts where people were having similar problems, but no one could offer a fix to the problem.

Is my problem something that is not practical to fix?

I can't afford to replace all fuel and electrical systems from front to back. A few years ago I tried to obtain a service manual for this car and found that it was only avail from Mercedes for what I think was a high price.
On this site I have seen repair manuals on CD for about $50 or so. Do these provide good complete coverage of the whole car?

Any ideas on what I can rule out as being the culprit?

Any help greatly apreciated.

Bill