Nailing at idle......OM606

[99E300d]

hi, I have a 99 E300D ,so far this yr replaced fuel ,lines o-rings, glowplugs, rear bearings(pita)
thanks to all the helpful posters! Now to the problem I created , ran some diesel purge thanks to helpful pictures in forum did wonders , but still had a small bit of nailing at idle , so pulled injectors took to shop only to find out everythings perfect with them and the shop didnt charge me which was nice!(kinda was hoping for one bad one to cure noise at idle) well went to dealer picked up some seal rings to install injectors back , did this started it and loud now thought ok air in system give it the old italian tune up on highway will clear this up, it didnt now ,at idle its loud ,what could i have done wrong it has power just idling nailing or knocking sound like truck ! any help would be greatly appreciated