2012 chevy 2500 cold air intake and exhaust installed now acts up on highway

[orange72sub]

I have a friend that bought a new 2012 2500 standard cab long bed 4x4 with the 6.0 auto. He added a free flow exhaust and a K&N cold air kit to it. Now when he is driving say down the highway and he backs out of the throttle the truck down shifts and it gets confused as to what to do next. He was told there's not enough back pressure and the computer is trying to compensate for that. They also told him the only way to fix it would be to go to a programmer and tune it to fix the problem. Has anybody dealt with this problem and if so how and or what programmer would you suggest? Thanks for any help.