Well as it turns out I wasn't getting any air into my system. Turns out I had a couple of bad glow plugs. A classic indicator of "Just because the light turns on doesn't mean that it works...." On the bright side I did swap out the original 300D fuel pre-heater for my newer (Cleaner) 350SDL one.
For the first time in my life I own my own multimeter. I'll be putting it to future good use
