'94 6.5TD problem
 

Hi guys.
I bought a '94 Chevy 2500LT with a 6.5 TD as a backup in case my dually went down.
The truck has problems and I need help. :)
BTW, besides turning up a Cat 3406, I know nothing about diesels.
This is what it's doing and what i've done so far:
The engine has 212k miles, and it's missing, smoking, has fuel in the oil, and is vibrating.
Everyone said fuel injectors. So, I loosened each one to see which one(s) were bad.
The two rear ones on each side didn't effect the engine any when I loosened them, so I changed them out.
Same as before. I did check one I put in, to see if it would idle rougher if I loosened the fuel line, and it acted as before. No difference in the way the truck idled. Bad injector maybe?
I didn't check the other one to see if there was a change in it because it's a pita to get to, it's the back one on the passenger side. I will, i'm sure, if I can't find anything else to check.
Truck takes a few to start if it sets for a week or two, but after starting, then it starts right up.
Since it is a '94 model, I don't want to spend a fortune repairing it (which is why it isn't in the shop :) ).
Any help would be appreciated.