vibrations after new converter an flexplate

[Sequential6.4L]

Whats up guys haven't been on here in awhile but im needing help with an issue so here I am lol. I Installed an ats built trans, converter, an flexplate an all is performing well but now the truck has started up with a vibration issue since I installed these parts, it idles slightly rougher which is just barely noticeable but from right off idle up 1100 rpm its got a pretty good shake to it, you gotta progress through the throttle pretty slowly to notice but it defiantly ain't right, after 1100 rpm shes nice an smooth all the way out to 3500+ .. any ideas? Nothing really noticeable while driving either just mainly does it when revving in neutral. Truck also sat for a long time, was thinking of any possible fuel/ injector issues? No engine light or trouble codes. Also recently passed a cylinder contribution test at the dealer when it was in for other repairs so im thinking the issue has gotta be the trans. Thanks for the help.

 

[White_monster]

Maybe the dowel pin hole is in the wrong spot. Something slightly loose?

 

[Sequential6.4L]

The Dowel for the flexplate? Being that there just one wouldn't that mean you couldn't put it in wrong? The engine was pulled after the trans install so hopefully me and the dealer aren't retarded and had something loose twice. I know ats doesn't have a great rep but I'd atleast expect they'd have things balance properly. Im gonna have to call them an see what they say im worried about trashing my crank bearings