Update on my 350 SDL ...
R&R intake manifold and removed at least 1.5 pounds of crud ... coked oil, from the looks of it. Machine shops dipped and cleaned it for about two weeks ... then I chipped and swabbed it until generally clean (no chunks to ingest). Both the vacuum fitting and the pressure sensor in the manifold were very nearly covered ... likely was still getting some function ...
Question: what does the vacuum fitting provide to the control system?
I replaced the glow plugs (just easier with manifold off) and it does start and idle smoother. Process of R&R was pretty straightforward ... biggest issue is remembering where all the little fuel line clips go ... replaced all of them as they were very brittle and most broke on removal.
1991 350 SDL (200K and she ain't bent, yet)
former 2002 E320 4Matic Wagon - good car
former 1985 300 CD - great car
former 1981 300 TD - good car
former 1972 280 SEL - not so good car
a couple of those diesel Rabbits ...40-45 mpg