I agree with everyone. Diagnose it, starting with a wet dry compression test. Even if it's perfectly fine it's nice to log those numbers.

Getting through that is no minor baptism. Broken manifold studs, tool won't fit, the EGR tube, header bolts, the whole Mary Anne! Really better done with someone who's been there, but hey, you have us! It's the really stupid, unexpected little stuff that that will harden your steel. The hard stuff is easy.