So i picked up a '97 lx450 dirt cheap on a whim and have been fixing some smaller issuse but the main issue i havnt yet tackled is the engine noise. Id call it a tapping, present at all times, sometimes barely noticeable, sometimes quite loud, increases with rpm. Seems to be from top end, towards the rear. Also worth noting, engine has normal power till it warms up, after that its probably the slowest vehicle ive ever driven. I havnt had the time to tear it down yet and i am unfamiliar with this particular engine. Any ideas or insight would be greatly appreciated. Im hoping its something simple. Thank you