2013 VW Passat 3.6 with 150k miles, DSG auto trans - Any ideas at what is causing a light rattle (like a clattering) at mild acceleration 2-2.5k RPM's only, then goes away? It doesn't sound like pinging/detonation issue and only happens when vehicle is warmed up, and can be in hot or cold weather. The clattering is not intermittent, and will always occur when driven at speeds above 25 MPH. 

Other info: Runs well - no CEL, premium fuel used, oil changed regularly 5k miles (M1 0W-40). Have checked for loose heat shields etc, everything is buttoned up. 

Possible ideas: intake carbon, loose timing chain or chain guide tensioner, or some other intake anomaly

Thank you!