Forget diesel I6 injectors. Get them from Greazzzer and don't worry about it. You're not going to make big power with this motor. Doing so will require a $$$ injection pump. Keep it stock and enjoy going slow, making smoke, and bulletproof reliability. Don't be surprised if the lower end makes it past 400 or 500k with just oil changes.
Air bubbles in the clear filter are normal.
GP's, a valve adjustment, fuel filters, and injection timing adjustment will likely clean up the idle. Also, the throttle linkage is a bit finicky and if set wrong can make the idle really shaky.
Stock AC on that TD is crap. It's probably a junky GM compressor that's either already dead or will crap out in the near future.
Stock tranny isn't terrible, but is a hassle to adjust and get right. The low RPM shift points are annoying and adjusting them out allegedly causes premature wear on the trans. Pretty sure my 722.3 made it past 300k. I just dumped $1600 into a full rebuild and install. The tranny shop, which specializes in 722's says after 150k, they often need a rebuild. If you're doing this on the cheap, there is a shift kit available on Amazon. Lotta benz guys swear by it. Plus, you can clean out your valve body when you do trans surgery - there is definitely a buncha crap.
Be sure to clean out that turbo vac line that goes to a banjo bolt somewhere near the injection pump. Can't remember what it it's for off hand, but it often gets clogged and results in low boost.
Lastly, go look up how to adjust the ALDA valve. After you tune everything else up you might consider adjusting this a little bit. Sometimes if you give the motor a little more fuel it can output more without making hecka smoke. If you go crazy with it, you're just gonna be an idiot making clouds of crap...
I'll probably go with the tranny as-is for now. If I hate it I'll probably try and find a merc 5 speed or something.
It idles rough cold, and a little rough warm. Fires right up (Better than the D24 ever did) and has good power. When I rev it I can see air bubbles in the clear fuel line that comes off the filter housing. I'll see what else the engine needs when it comes out. Odo says 200k but PO said he swapped the cluster, so I'm gonna say it has at least 300k. He also said to find myself some diesel I6 injectors if I want to make power. The manifold looks like it could be a problem if I wanted to put an intercooler on it, the turbo feeds directly into it from underneath. I dunno what an N/A intake looks like, but that could be a solution.
I'm wondering what to do about the throttle, the Merc's throttle is just a rotating stick that comes out of the firewall. I'm also wondering what to do about mounts, power steering, AC, driveshaft, shfiter, etc... Are there really no documented Volvo Merc motor swaps?
Also yeah, the D24 leaked most of the time I had it. Finally fixed the valve cover leak and then the engine decided to break. Thanks VW.