Hi guys I'm pretty new here but have found some useful info here, but now i'm stumped. I have a '05 Sierra 1500 with a vortech s-trim on it with the diablo tuner. The truck has been running solid ever since vortech installed the kit but just recently my tranny has been slipping bad in the 1-2 shift and 2-3.... My fluid was burnt so I got it flushed. That helped it a bit but it didn't fix it, and it's worse in tow-haul mode.
I don't know much about the 4l60 so if anybody has any advice it would be much appreciated.

Thanks,
Matt