http://www.youtube.com/watch?v=wCbi3FnuhTM
I've tried a lot of stuff: Cleen from GM in the intake, Seafoam spray, seafoam on the gas tank, higher octane even if its not recommended and the problem is still there since 177 000 kms and the car has 294 000 kms now. It does that rattling sound only when low to medium acceleration.
Its a 2005 automatic Cadillac CTS 3.6l non-DI.