Awesome site, thank you. Vacuum gauge shows 18psi steady at idle, but there are still a couple of vacuum hoses that might have a leak. I'll get those replaced and do a compression test tomorrow. (also just to clarify, exhaust manifold is the one with a small crack, intake is fine)
It also crossed my mind that cam timing could be off, I'll check that while I have the plugs out for the compression test.
Another thing I've been wondering - do those fuel pressure number look okay? I've googled extensively but have seen everything from 45-60 under boost called 'normal'.