[sandbox]

Please help me figure this one out. I finally got my Cobra on the road last month after a seven year build. I'm running a mild 460 with a C-6 auto and a narrowed Mustang 8.8 rear. The engine runs smooth at idle and fine when I crank it up in park or neutral. When I take off in drive, up to about 30mph the whole car SHUDDERS like crazy. Then it smooths pretty much out and will accelerate fine. What can this be and how should I go about eliminating sources one by one? Thanks for any help.