2004 X Type 3.0L w/130k miles, synthetic 5w30 (changed frequently).
No codes are being thrown.
OIL LIGHT works but DOES NOT COME ON when this happens.

I get a slight knock that reminds me of a bad timing chain tensioner sound. The noise generally will come just as the engine is coming off the torque range about 3-4 seconds before shifting gears. (Not under heavy load, and not when you let off the gas). The intensity of the knock varies, even with the same load and sometimes it's not there at all, other times it's quite noticeable. If it's quite noticeable, I can let off the gas then immediately depress the gas and it will usually go away or get noticeably quieter. Once it shifts, the noise is gone again.

Keeping that in mind, there have been a couple of times over the past 5k miles that I started it and it immediately started knocking quite loud! 1-3 seconds later I shut it off, try again and get the same results. No oil light but certainly a metal type knock. I start it later that day and the noise is considerably quieter then slowly starts going away.

If it were a rod knock, it wouldn't be changing and going away at times. It doesn't do this under a heavy load like a main bearing would. I doesn't knock at high RPMs like a rod would. I listened with a stethoscope last time and you could hear it everywhere I put it at the top of the engine (valve covers, timing cover) but it didn't get louder as I moved the stetho so I don't feel I was close to it at any point... then the noise started going away so I was out of luck.

Any ideas?

Thanks!