Hi there folks, I have a 2013 500 Abarth @ 67K that seems to be losing its mind all of a sudden. Within the last few days I've been getting seemingly random CEL's, yellow triangles, and messages. The engine will also stutter/lose power along with backfires. a handful of times now it has completely or partially stalled with a blinking CEL until I pull over and restart. Some examples of the messages are ESC Unavailable, Hill Start Unavailable, High Coolant Temp, and Fuel Cutoff Unavailable. Which ones appear is inconsistent and it's not always all of them that appear at any given moment. It certainly seems electrical, and looking through other posts I've done the following things:

Replaced the battery
Cleaned the main ground going from the battery to the chassis beneath the tray
Cleaned the small ground going to the ecu
Cleaned the ground ribbon from the the chassis to the trans
Wiring going to the hatch. Did find the large black wire partially damaged, so I covered it with electrical tape for now. The other wires all had intact insulation.
I did have an aftermarket stereo. All of that wiring/the stereo has been unplugged.
I had a Madness GoPedal installed, that's been removed.
Had aftermarket LED headlight bulbs, those have been removed.

Anyone have any ideas? I'm grasping at straws at this point