All kinds of codes popping up stutter or very slow acceleration?

Hello, are all the codes for the Instrument Cluster or are there codes in other modules as well? And if so, what are they? It sounds like a communications issue so if there are any "U" codes, we would probably look into those first. If theres corrupt messages on the network, it can set codes for pretty much anything. And if I can get the vin# too, it will make looking up this specific vehicle much faster and make sure we are looking at the correct service info. There are too many versions of this model, so we need to look it up by Vin.

Here are some diagrams of the GMLAN Low and High speed networks, along with the Splice location (SP200) where all the Low speed modules wiring meets up and modules can be unplugged one by one to isolate issues. And I added some operations info as well. But if we can get some U codes to go by, at least we will have a bit more direction.