I just bought a 04 BMW E46 330i with the sport.

I just bought a 04 BMW E46 330i with the sport package, It sounded alright when I got it but then it makes this noise only at idle and when I rev the engine it goes away or the noise diminishes quite a bit. Also the engine does not make the sound right at start up usually when it gets to normal operating temperature does it start making this noise. The noise is like a galloping, rotating chain clanking, slapping noise, but it sounds fine and when I put foot on the brake and rev the engine and it also goes away and when I rev the engine. Does not sound like a vanos rattle or chain tensioner noise I just replaced the primary chain tensioner and it quieted the noise quite a bit.

here is a video of the noise
http://www.youtube.com/watch?v=f_tnQRQt6BI&feature=plcp

here is a broken link just incase I can't post links yet

hxxp: // w w w (dot) youtube (dot) com / watch?v=f_tnQRQt6BI&feature=plcp

Things I have already checked or changed

-DISA
-Idler Pulley
-tentioner pulley
-Water pump
-thermostat
-radiator flush but not the engine block flush
- changed the oil
- belts and pulley all are good
- fan clutch seems to check out fine
- I have heard it could be vanos seals but that is a different rattle from what I can hear.
- doesn't knock with acceleration so don't think it is the rod knock

Please help this probably will only be able to be answered by a BMW enthusiast because I have asked numerous people and they can not figure it out and I have changed alot of things and they made no difference.

Please help

Thank you
Brandon