I have an 04 Sierra 5.3 with a 2-3 shift flair. GM rebuilt this tranny under warranty. They did not touch the valve body due to a shift kit. However, they put new clutches etc. (My buddy rebuilt it) As soon as I got it out of the shop, it still had the 2-3 shift flair. My buddy said to get a new valve body and bring it back in, he would install it. I did that. Still had the flair. So I got pissed and put in a new transmission. Still has shift flair.....BUT only at half throttle to full throttle. Otherwise it is perfect. What to do????

Side note. I had a cam, throttle body, air intake, intake manifold, and had it dyno tested. I developed the shift flair 3 months after all of this work. So our company cars got taken away and I had to start driving my toy....went totally back to stock..even with factory programming. The shift flair is the only thing that has stayed with the truck.