Remember that the advance works off ported vacuum, meaning that it increases, and advances the timing, when the throttle is opened. You should hold some vacuum at the distributor, but I forget if it bleeds down slowly or not. So if you are not holding ANY, then you should replace the dashpot.

The best test would be to give it some vacuum with the Mityvac with the engine running and observe the effect on the timing.

It would certainly contribute to the problems you describe.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe