Sorry I didn't keep in touch with this one. I had the same problem and replaced the delivery valves O rings and crush washers and the rocking went away. That engine rocked the car at the stop and gave the car a very slow and almost unresponsive start. Excellent tutorial for this one on this site.

I also have a second set of these O rings and washers ready to go if I see this problem again.

I also replaced all the fuel line filters and fuel lines in the engine area. Before all this, I wanted to blame the fuel injectors for this problem, but it wasn't so.

Pabster
1997 E300D