Car shutters when leaving from a full stop??

[93 Cobra needs input]

Last weekend I put a new tremec TKO in my cobra. I got the cobra R bellhousing and a new ram clutch disk that fit the tko splines I did use my stock pressure plate. I put everything together moved my crossmember and things were looking good till I drove it. When I take off from a dead stop the car shakes for a couple of seconds untill it get rolling then its fine, Tranny shifts ok and doesn't make any noise after the car is rolling. If I rev the motor higher and let the clutch out fairly quick it won't do it, only lower rpm's and slow clutch engagement. I have new u-joints and a new pilot bearing. Could this be the clutch needing to seat? I didn't turn the flywheel, car had only 70k looked perfect and in 2 months it is going to be stored and a 28oz balance new flywheel installed. This is kinda buging my and really anoying any coments sent my way are helpfull thanks.