vibration above 3500 rpms??

I recently put in a spec stage 4 clutch and steel flywheel in my car about 500 miles ago. This weekend I decided to get on it a little bit for the first time. Well as soon as the rpms got to 3500 the car started vibrating. It goes away as soon as you push in the clutch. Has anyone had any problems with the stage 4 or flywheel being out of balance? I know it is one of the 2 because it does starts vibrating as soon as it hits 3500 rpms in my driveway. Thanks for any help!!

any ideas???

just to give a final update, the car is finally fixed. i ended up sending back the stock flywheel and the new spec flywheel back to spec. they matched the balance on the new flywheel to the old one. its finally good to go now!