No wonder it won't run
Strelnik has some good advice for getting it started. Since your injector lines are removed, he (or someone else) may have some steps to take first to narrow down the potential issues. There are a lot of things you can do before you have to spend any money!
(my .02).
Other than that, I think the consensus is to get that baby home and use this brain trust (not me) to diagnose the problem(s).
I too have a feeling the mechanic was buying more time stating the injection pump was bad. If it's leaking air bad enough to not stay running, I could understand how one might think the injection pump is not doing it's job.
Keep us posted and use lots of pictures to describe symptoms and what you've done. Good Luck!