07, NBS, Silverado, 4.8 tuning problems:
I have eliminated the weak throttle response and installed a servo to speed up the slow 1>2 shift. Torq. management was reduced to 0. The truck had a dead, hanging throttle and refuse to shift at wot. Installed stock tune, still will not shift at wot. WTF
Tried all kinds of tuning to fix this and found out you need 10% in the torq. reduction abuse mode to solve the dead, hanging throttle. The tune would not work until the TCM, ECM, and Throttle control fuses were pulled for 30 seconds.
This also solved the wot shifting.
I would recommend anyone having problems with the Gen4 tuning do this and save yourself the frustration of installing tunes with no results. For some reason the Gen4 truck has some weird things going on.
If anyone has had these problems let me know. Is this just a Gen4, 4.8 issue?

Dan