'82 300D no start. tried afew things, whats next?

[bungeekord]

Hello all,

Ive got me a 1982 300D turbo, a friend of mine gave it to me after a coolant line cracked, engine overheated a little, then not being able to get it start for a while. He got frustrated with it, and someone gave him a gas car, so he passed on the karma (and the Mercedes) to me.
Its been running great all summer, I was able to get it to start shortly after he gave it to me, but it recently crapped out on me and I cant get it to go. heres the scenario:
1st off, Ive been cutting diesel with 50% veggie oil (settled, and passed through a 5 micron water seperating filter set up). I have no reason to believe this is to blame for the car not starting however (please correct me if Im wrong)
So, I went to start it the other day, and it would start for a few seconds then, cut out. it usually starts hard, so Im liberal with the excelerator when starting. after trying a few times it caught and ran rough for about half a minute, pulling out into the street from my driveway was my big mistake. It died 20 feet down the road. then it would start only for a few seconds then die, it did this untill it just wouldn't start at all (still turns over though, those batteries are hardcore!). My first diagnoses is air in fuel lines. fuel guage read above R line but below 1/4 tank, its gone lower before but its a bit quirky, and I dont entirely trust the little bugger.
In priming the fuel line with the pump between filters I noticed the primary filter was filthy (I hadn't changed them since recieving vehicle). I changed both filters with no improvement in starting. Next cracked injectors and turned engine over (pre-glow) to purge air out of lines between pump and injectors. Fuel was visably running from the 3 lines closest to the firewall but not the other 2 so much... not sure what that meant. reconnected and nothing...still.
I have noticed the glow plugs are not feeling hot to the touch when initially turning the ignition, and the relay goes about 20 seconds before popping off. I have checked the pins on the relay and they all have 12 volts as well as power source to relay and the fuse, testing the resistance of the glow plugs I got 1.5 ohm, is this too high? With relay on they recieve 12 volts... My friend claims that the glow plugs are relatively new as he had to replace them when dealing with this thing not starting for him...
I had a diesel vw a while back, and this thing had a stop solenoid connected to the injector pump, this thing was faulty once and the car would not start. I know the mercedes solenoid is vacuum opperated, but where are these vacuum lines and could this be my problem? If my problem is the injection pump itself how costly is that job (its probably too much for me to do myself)?
if anyone has advice I'd sure appreciate any help I could get. I've been looking through a bunch of past threads, but cant find anything quite applicable yet...
thanks