Common problem I had with my 2.1TD was air in the fuel lines. Often caused by aging fuel line junctions and higher than average negative pressue in the lines. This is commonly caused by a mesh filter in the tank that is part of the fuel pickup and sender unit.
Also, there is commonly a poor fit of the fuel filter housing cap. A good quality new filter and O'ring will often fix this. Check also, the fuel bleed off pipes on the injectors, these perish and are so cheap I'd recommend just replacing them anyway.....don't bother trying to inspect them, the pin holes are often too small to see so just replace them.
I'll need your email address to send the epic manual as the file is of epic size and the forum won't allow upload.
Cheers and good luck.
Dave