Recently bought a 2000 GT 4.6L 2V after replacing the extremely loud idler pulley I started hearing a very faint rattle noise coming from the front of the engine. The rattle is only noticable around 1300rpm when the engine is coming down in revs. I hear the timing chain guides in these are notorious for breaking but any bad timing chain I've ever heard was a pretty noticable slapping noise and usually consistently makes noise throughout the rev range. I've taken the belt off and still heard the noise so I pretty much cancelled out pulies. Does not sound like it's coming from the camshaft, I don't see any shiny metallic flakes on the dipstick.
​​​​​So my question would be is there any small things I can check before having to tear into it?

 

pull the valve covers and timing cover and inspect. The chain guide probably lost a few pieces of the plastic.