2001 chevy tahoe ecm fried?

[getem97]

why would my 2001 Chevy Tahoe LS 2wd be throwing random codes for transfer case and 4x4 system out of nowhere. I had the security system disabled and added a custom tune. Deleted cats and downstream o2 sensor's, Changed shift point's, and changed tire size. It consistently 30 to 40 completely random codes at all time's. I have pretty much rebuilt the engine trying to figure out the misfire issue, I have also been through every ground on the truck. I only use acdelco gm replacement part's. I have replaced everything and I'm disappointed immediately every time. 

[bshort]

Maybe there's an issue with the T-case or 4x4 system?  Mine has more than a few electrical components and sensors to it.  (1999 Sierra)