81 VW Rabbit Diesel

I bought it from someone who let it sit for too long. I have got it almost road ready, but have run out of time and desire to work on it.
New master cylinder, couple of brake hoses, rear drum caliper, brake pads, fuel hoses on engine, fuel filter, glow plugs, glow plug relay, battery, tires, etc.
It is still taking in air from somewhere. I had it driving, but it died on me. I think the leak is either between the fuel tank and filter, or a vacuum hose.