IV RECENTLY BROUGHT A S2 RS TURBO BUT WHEN IM DRIVING IT THERE SEEMS TO BE A KNOCKING KIND OF NOISE COMING FROM THE ENGINE , SOUNDS LIKE THE CAM . IT IDLE'S SPOT ON BUT IT ALSO SEEMS TO HOLD BACK MAINLY IN BETWEEN 2-3 RPM LIKE ITS MISSING . WHEN ITS GETS PAST 3OOO RPM BOOSTS & SOUNDS BANG ON ? CAN ANY1 HELP ME B4 I GET A SLEDGE HAMMER OUT