As the engine was worked on, many parts got repaired and replaced. Cracked expansion tank, radiator that I put a wrench through (expensive mistake!), vacuum pump (old one was fine, but was original), engine and transmission mounts and shocks, belt tensioner, valve cover gasket, and of course new head gasket and studs.
Engine still ran like hell. Shaking, rocking, missing out like hell, smoking like a train, refused to idle, stalled a lot.
Turns out the original injection pump had a rear ball bearing failure on its camshaft. How the car ran is a mystery, but it did. Cylinders 1,2, and 3 worked, but 4 was intermittent, and 5 and 6 had dead skips despite having good compression and good injectors. Originally thought it was fuel pressure related due to the overflow valve being wide open so I installed a new one. No help.
Decided to go the used IP route and took a gamble on one from fleapay. Seller guaranteed it and it came with some extra spare parts that were useful to me, so it was a calculated risk. Got it installed and guess what....it would run on all 6 cylinders, but it REFUSED to idle and REFUSED to rev up! REALLY WEIRD! Eventually tracked it down to being a tired IP and had some varnish sticking things together. In addition, the NEW (Mercedes OEM) POV turned out to be bad!
http://www.peachparts.com/shopforum/diesel-discussion/381625-om60x-pressure-relief-overflow-valve.html
Tired of fooling with it, I placed a WTB on this forum and wound up with a good working pump from a 350SDL (more on that later). This time, there was success. Car ran like it was supposed to and on all 6 cylinders. Idle good, revving good, smoke much more tolerable.
At this point, the engine got reassembled and all the auxiliary bits reattached, rubber vacuum fittings replaced, and missing items like the washer bottle reinstalled in the car.
In an attempt to track down some electrical gremlins, I started a post (my first post on this forum in fact) in May regarding a fuse that kept blowing.
http://www.peachparts.com/shopforum/tech-help/377913-86-300sdl-popping-fuse-11-a.html
This was a problem since every time the headlights were turned on, the fuse would blow - taking out the right side turn signal and parking light. In Texas, that's an inspection failure, not to mention I'm not a fan of using my car with blown fuses.
Ultimately I found faults in the headlight wiring due to a chafe and discovered a melted mess of wires in the fuse box. I cut out all the bad wiring and replaced, but still had the fuse blowing. I eventually determined that the fault is in the right side headlight wiper motor. The wiring harness is good, but the motor reads shorted, so it is unplugged for now. The fuse I pulled out of the holder when I got the car was a 25A fuse, when the legend calls for 8A. I'd imagine that was the source of the melted wiring!