Let me know if cleaning the injectors fixes your problems. If not it's deeper into the fuel system.
Mine was parked for a long time, by the time it was all said and done i had torn down, cleaned and resealed the Injector Pump, flushed the Injector Lines and Cleaned the Injectors.
Does your new "toy" still have the Glow Plug Controller? If not you'll probably want a set of 12V Glow Plugs. NGK part number 7880 Y-710J

IIRC they're for a 1987 Isuzu Diesel, but they're a perfect match for the 6V Glow Plugs in the 4D55. I searched high and low for ages to find a set of 12V plugs for it, ended up finding the answer on a Chevette forum

Which ended up being those NGK 7880 plugs.