After re reading.. it looks like your issue may have a little bit to do with colder
cooler ambient temps.... Which to me signals a LEAN condition.
You should look at your LTFT for both banks and see what they report.
It might also be time for new upstream Oxygen sensors. They are a wear part.
At 105K I wouldn't think that you have any bad fuel injectors for coil packs, but that
said anything is possible.
I would try some "good" premium fuel (less than 10% ethanol) and some Techron Concentrate.
2 tanks in a row and see if that changes anything. Then i might think about spark plugs
and wires- use AC Delco irridiums (not from amazon) but from a local parts store
or somewhere like Summit Racing that won't sell you counterfeit parts.
Which Transmission Do you have ??? (I'm assuming 6l80e, but don't know for sure)
The torque converter strategy on the 6 speed is goofy from the factory !!