Ailing engine (Updated after teardown)

This may sound stupid as each cyl is individual, but is there a way 4 or 6 contribute/feed to higher #'s on 8?
Good news that nothing seems too obvious(besides 4/6), but a head scratcher for sure
Yup and it's not stupid. That's a smart question. Adjacent cylinders and sometimes even those across from each other say on shared intake runners can affect each other. I don't think you'll see across cylinders affecting each other on a single plane intake, though.