vacuum advance idle issue?

Timing light revealed both factory tdc 0 marks as well as the previus owner painted on marks which it was ruunning at vaccume unhooked ALL to be off true TDC of cylander #1. with timing set according to the book and actual TDC all is standard procedure untill the advance is hooked up...ill post a pic tommorow when there is light...looks like a later model stock electronic distributer...could one of the weights/springs in the distributer cause this low end issue and not present itself at speed? Tganks for evrybodys problem solving insight and genius on this one..