Sheesh, isn't anyone going to actually HELP the poor guy instead of bashing his car? If I understand correctly, the problem started after the "seals" on the top of the pump were replaced. I'm assuming delivery valve seals. There is a VERY specific method for torquing down the barrels after replacing those seals, it is only found in the TDM (Tech Data Manual). Something like torquing to spec, releasing, torqueing again, releasing, then doing it a third time (can't remember exactly). If this is not done BY THE BOOK you can get problems similar to what was described. There was a recent post detailing this procedure on the MBZ.org diesel list, but I don't think the archives are back up yet since the server crash.
BTW, the metal lines only need replacing if they crack or break, so I'm guessing you have the braided-cover rubber return lines replaced. (?)
If the above is NOT the problem, I'd check motor mounts, timing chain stretch, and IP timing before replacing the injectors. Next up would probably be new injectors BUT a new set must be calibrated (all set to the same "pop" pressure) on a test bench, so buy them from a diesel shop that will do that before they install them (or give them to you to install). If you can get them matched to less than 3 bar variance, you should have a smoooooth idle. I would NOT replace or rebuild the IP ($1000+!) unless you have significant proof that it is indeed bad! That is very unlikely... but it would "fix" the problem if the original shop didn't torque down the delivery barrels properly!
Now, as to Tank's ranting, I agree that the OM603.97x was flawed. I also try to dissaude people from buying cars with those engines. HOWEVER, if someone already OWNS the car and obviously likes it, we should try to help the guy and not tell him to "sell his POS!" The 90-95 S-class diesels are nice cars (especially the 140), and some of the engines DO survive without bent rods... just my $0.02!
Regards,