Fpr is pretty much the only way to get fuel in to the crankcase so swap that out and you’ll probably be ok
This makes logic. Only path I can see for fuel to get where it's going.Check your fuel pressure regulator on the left side of the fuel rail. Pull the rubber hose off the left side and turn on the key to cycle the fuel pump. If fuel drips out of the curved pipe on the FPR then its bad. When the FPR fails it dumps excess fuel into cylinders 1&4 through the vacuum lines and the fuel will leak past the piston rings into the crankcase.