is your rad cap working and letting pressure release at 15 psi ?

have you removed spark plugs yet ? if water ingress caused misfire you need to isolate which cylinder it is. could be leaking headgasket, cracked head or block.

ive seen cracked wet liners do it a few times on big diesels, with the misfire and loads of pressure its likely water in a pot but needs to be diagnosed and isolated 100% before stripping it ime.