Ah, that could definitely be…I was thinking Tom was describing an ECM fault of some sort. Admittedly, im not up on the variations tcm/pcm shift strategy tables applicable to most of these vehicles as I do only bench-carry out builds.I believe he was refering to Torque Management cutting power between shifts.
My 06 Silverado with a brand new 65e has laggy 1-2 shifts at anything under half throttle. Ive looked at the shift times completion table and out of tow/haul mode it is factory set for .6 seconds under half throttle. So that could be part of his problem. My Tahoe is .49 why it is different i have no answer
Perhaps a TECH2 scan and reflash or update may help the OP’s 1-2 shift situation or at least rule the TM out…