Loss of power everything in cab, power steering, ac etc…

[Jessekey7]

2017 gmc 6.2 - I’ve done the grounds by the tweeters. I’ve done the ground by passenger front tire, I’ve done a new battery, I’ve done a new alternator, I’ve added a extra ground cable, I’ve replace my entire stock ground cable. How do I fix this dash/ ac/ power steering/ stabilitrack/ trailer brakes/ charging system fault / and everything else this truck is doing while driving. I’m about to the point of trad in. 
mused to do would only lose power driving motor never die, but inside everything sucks off and turns back on. Can hear the clicking like when you first start the truck every time. I can have it in park and rev the truck up and as soon as I let off the gas it does it all just the same sitting still. Turning and driving around town the stability rack will flash to service and then the gauges will go out. 
someome please help before I spend an arm and a left to fix or trade in and lose my ass on trade.

[rav3]

Can I assume you have check for any codes? How many miles? Any after-market stuff done or added?