I replaced all of the pulleys, belt tensioner, and new belt a few thousand miles ago.

I did what you said and rechecked everything on the front of the engine and everything is tight, no bearing noises or belt slipping etc. And the noise is definitely coming from the top of the engine near the firewall, its hard to nail down exactly as it doesn't always make the noise.

I'm going to try the ester oil next oil change. Its odd, to me it just sounds like overall the timing is off. Even on slow acceleration it sounds like its off a bit. If the guide is broken or sticky, could it have caused it to jump a tooth? is there an easy way to check this? I remember the 350z had covers on the front of the engine you could remove, but I know the 370 doesn't have those...

If something major (like jumping a tooth) has happened, a DTC should have been thrown. If you haven't scanned for codes, that would be a good place to look.

Yep.. scanned with a snap-on verus, no CEL and no stored codes...

Its getting the roof fixed right now (car wash entrance door went into neutral and came down on it, luckily doesn't need replaced, just dents removed and repainted, $1,292, and car wash covered it all...)