I agree the cleaning oil is not going to fix the OP's problem, but the ticking/knocking sound could also be a failing rocker/follower which can lead to rapid engine deconstruction. This happens most often on the passenger side head as it is the last area to get oil from the oiling system and starves for oil. The low oil pressure likely is largely due to the timing chain tensioner seals blowing out which causes lack of oil pressure and flow to the
OP, here are a couple of videos to check out:
In my opinion, a high mileage 5.4 should not be running 5w-20. Mine has had 5w-30 for most of it's life (270k miles) and hasn't developed timing noises, knock on wood, and still has 25 psi hot idle oil pressure. I would probably use a 0w-40 Euro type oil if I was trying to limp a tappy/knocky 5.4l along.