DPMS556

I recently purchased a 2007 Tahoe LT and changed the front drivers side hub assembly because it had play in it. Once I got it put back together it drove fine for a day, then the problems started. Its giving me the codes for Traction Control System, Stabilitrak Off, and Check Engine Light. The truck is shifting hard from 1st to 2nd, and has a miss in cylinder 1. It has a very rough idle also. Ive called multiple GM service centers, and their all telling me i have two seperate problems even though they started at exactly the same time. Whats confusing me, if it is two sepereate problems, why would a miss in cylinder 1 cause it to shift hard from 1st to 2nd. this problem has got me extremely frustrated. Any help would be greatly appreciated.

Dan.