I have exactly the same issue with mine once engines fully warmed! changed everything you have listed also.
my missfire is at around 4.5k.

Only thing left to change is the blue sensor as i fitted an unkown used one when i rebuilt the engine. I have a brand new msd one sat here but its a pig to get at and its cold outside in the garage

Will be interested to see if this solves yours.

i disconnected my amal valve so it just ran like 9psi and it didnt missfire at all, all the way to rev limit. however engine temps will remain alot lower at that sort of boost so still hasn't really shone light on the issue.

Good luck anyway mate.