Help with r33 fuel issue and knock

[Wiso123]

Help with r33 fuel issue and knock

My NA r33 has been having troubles, replaced the fuel pump as that died as well as the filter, ever since it is running terribly, then I noticed that after reving it slightly, when you come of the throttle you can hear a knock coming from the head that sounds like a train going over train tracks. It ran perfectly a few days ago and had no knocking issue, I then went to test it again today and the same issue. I have no clue what is going on here and don't want to keep replacing things that I don't need to replace

[tridentt150v]

I am thinking you have much more than fuel issues dude!!!

Either a camshaft has snapped [absolute best case] lifter has gone [best case], a valve has gone [getting colder], or a piston has gone = at least a top end rebuild.