I have an '09 2500 Vortec 6.0 with the 6 speed auto. Don't drive it that much, use it for a tow vehicle pulling my 27' travel trailer. When I do drive it I notice that it doesn't shift very precise in the lower gears. Seems to slide from 2nd to 3rd and vice versa. Also to the point of feeling like it looses power. I have taken it back to Robert'* Chevy in KCMO where I bought it but they tell me that it isn't showing a code. I have allowed them to keep it overnight and drive it when it'* cold as it is very noticeable then. They claim that it doesn't repeat the problem. I say BS, it does it every time I drive it. Granted I don't drive it hard at all. If I put the boot to it, the thing works fine. If I hook up my flatbed trailer and punch the tow haul button it'* fine. Mainly when I'm just driving around town.

Any complaints and or fixes for this?? Can I get a programmer and increase the shift pressure or something? I'm pretty frustrated to the point of dumping it for a Ford!!

You've got a truck, that drives like a Cadillac, that'* built by GM. It sounds like it'* shifting easy under light throttle, and power shifting when hauling a trailer or hauling @$$. That all seems pretty like normal GM transmission behavior to me. Believe it or not, modern truck transmissions are built to drive comfortably when empty, and under light throttle, especially GM. Unless it'* slipping after it finds a gear, I doesn't seem like anything is wrong. If you want it to kick into every gear with the slightest throttle, there'* programmers for that. However, you will wear out everything behind the transmission that much faster.