I suspect your problem is a very slight distortion of the frame, and you will only be able to get the car to track correctly by having someone who knows what they are doing adjust the alignment to offset this distortion. Setting to factory recommendations will not fix the problem, and I don't believe you will be able to completely correct the frame.
I'd call around to the better body shops in the area, especially the ones that offer frame straightening, and see who they recommend for alignments. I'm lucky here, there is a tire shop (Firestone dealer, of all people) who has a wizard working for them. I can't believe the job he did on the TE, and it only cost $35! I'm taking all the other cars down there one at a time as money and time permit......
Don't give up, but don't depend on the dealer, either -- our local one never seems to have the same techs from month to month, as as a friend of mine said, "I'm not letting at teenager work on my $60,000 car! Period!"
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!