Never knocks on a cold start. After I drive 10 or so min it will knock at idle and go away an 2krpms and up. Let off gas and as soon as idle hits sub 1k knock comes back. Mechanic thinks it could be duel mass flywheel (which is going to be changed with the clutch on Monday) But I cant wait that long for a diagnosis. Nissan will diagnose it for 100$ but its kinda far from my house and the flywheel replacement might be the problem. My question is this.. Is this a common problem with the clutch flywheel to make a knocking noise or is it likely to be something els? The car has 66k miles and (the motor) drives like a dream at high rpm's.

 

Impossible to even guess from your loose description of "knocking". It is NOT a common problem for a clutch/flywheel to knock, but even if it's not, a rod or main bearing failure causing a knock would be even worse news. If you can't wait until over the weekend to get a more definitive answer, you could get one when your revup blows up in your face. Better to be conservative with your driving and be sure to check your engine oil level.