Hi guys, I'm new here but not to diesels or forums. I have a BMW E34 and an old Toyota 4x4, both gas unfortunately, both to be swapped eventually (3L and OM606, respectively, but I digress...). I've worked on a few different makes of diesel engines, mostly old obscure stuff, and I've got a problem with a Mitsubishi 4D55 that has me tearing my hair out.

It's an 83 Dodge Ram 50 with a Bosch VE-style pump. It was running great until last week when it died climbing a hill. I cleaned out a bunch of goop from the tank-to-filter line, filter, and aftermarket lift pump that I did not reinstall. I put in a new filter, cracked the injector lines at the injectors, had someone crank the engine with the pedal floored, tightened the injectors when they began to squirt, verified fuel delivery by removing the glowplugs and observing four big white vapor clouds rhythmically popping out of the cylinder head (what a mess!)...

...but it barely runs. It'll start (cold, and with no power to the plugs), and it'll idle what feels like indefinitely, at least 3-4 minutes, but idle is low (about 600 when it should be 1200 with the high idle cable pulled). If I remove the skinny fuel return line from the rail, there's a drop of fuel about every 10 seconds coming out. If I press and hold the accelerator pedal, it'll rev a little bit and go back to low idle. When I release the pedal, it idles even lower and wants to die. Pressing the pedal again results in a half-decent idle but nothing more.

There's another 4D55 here that had the exact same problems after a head replacement. We eventually got it bled and it's been running great since, but I don't know how we did it and I'm stumped. The factory repair manual is worthless; doesn't even address the injector lines.

What am I doing wrong? I've successfully bled other diesels - John Deere, VW, Peugeot, Isuzu, Mazda/Perkins...