Is it me, or does it sound unbelievably noisy tappet-wise? When you went back into the car you could still clearly here it. I assume these have hydraulic lifters?
I'd certainly want to compare it to a well running car with same engine if by chance you know of one.
Not much point going further with electrical / fuel related issues if the basic mechanicals aren't right. If, say, you have hydraulic valve lifters that have clogged / stuck / failed you'll have all sorts of potential issues as a result of retarded valve timing and incorrect lift.
It might just be your phone / camera being very sensitive, in which case I'll get my coat, but I'd be interested to see how your car compares in engine noise levels to a known sweet example. These do suffer from piston slap at higher miles, but this sounds more tappety to me and you seem to have biblical compression. I reckon your engine thinks it's a diesel, hence the confused running
Good luck with it: there's nothing worse than doing careful diagnostics, coming up with a good theory, buying the parts, carefully fitting them (and finding the old part indeed looked a bit dodgy) only to find the problem remains.
Hopefully you'll have a breakthrough and all of your previous work will pay off in terms of a particularly nice car with long term reliability built in.