Diesel idling woes..continued

Thanks to all who have given me advise. to
recap, my 81 300D (240k mi) idles terribly rough. Jumps, misses and blows smoke when idling only. Smells like unburned fuel to me, very strong. When on the road, it runs smooth as silk. It just seems to take spells running rough at idle, but it is getting worse and more frequent.

Ok, I've taken out the injectors, had them cleaned and checked at a diesel joint. The man tells me they are fine! I was hoping something was wrong with at least one, to clear up my problem. Oh well.

What's my next step? I would think if something major was wrong with it, such as pump timing, etc. it would run rough continuously? Why only does this at low rmp idling, and not all the time idling, unless it's something minor?

Thanks
Phill