1981 300sd thumps at idle
 

Engine thumps heavily at idle, smooths out as rpm increases, plenty of power once you get past 10mph, but very slow take off, turbo spools up nicely, head has been rebuilt, new engine mounts, have checked the compression, its a little low but even across the 5 cyls., a bit more blowby than I would like, replaced injectors one at a time with some spare used ones that worked well in my 300d (no difference at any point), replaced gloplugs with new, new fuel filters, idle speed adjusted up, no signs of external leakage from the injector lines. what's next?:confused:

cigar hose