Hi Diseasel300 (cool name)! I do like to point out that I get her on the highway and above 70mph whenever she drives. On the last trip of the season last year I went for a 2+ hour continuous 75mph run (got up to 90 in a few spots) to blow out the carbon before putting her away.

You are right, the smoke is black, not white. It's not blue either, so it isn't oil. The state of the injectors is unknown to be honest.
What I do know is that the guy I bought it from 3 years ago totally neglected the car, so lots of deferred maintenance.

I don't have a pop tester. I assume there is no other way to test this? Can you replace just the nozzles, or does the whole injector (x5) need to be replaced?

Can they be rebuild?

My main concern is the ****ty starting. I don't honestly think it's glow plugs. It would run like poop in the beginning if it was glow-plugs, right? Which it kinda does I suppose, but only when in gear for the first 2 minutes.

__________________
"The MB W123 is so bulletproof, you can drive them forever. Which is a good thing as it takes that long to get anywhere."
Betsie: 1984 W123 300D (hobby, 280k miles)
Myrla: 2001 Mazda Protege 2.0 ES 5spd (daily driver, 130k miles)
The Turd: 2007 Toyota Camry (wife's car, 118k miles)