Hello folks, I've got a weird issue. I have a 2005 Tahoe with the 5.3L V8. I got it recently from a family member who had it sitting for about two years. When it was parked, the only codes it had were related to the ABS system. Now, it still has the ABS codes but also has a crap ton of sensor-related codes that instantly reappear after clearing the codes. Often there will be "too high" and "too low" codes for the same sensor. Every time it's an even forty codes on the engine module. Some people have told me to check the grounds and voltages. If I drive it around, it'll start misfiring. Didn't misfire when it was parked.

List of codes from the last time I looked. Read with a Zurich ZR8 in OEM Enhanced mode. Codes don't show up when in generic mode.

Every time there are different codes. Some will be the same, but never in the same order. I'll upload all the videos I took of reading the codes I've read.

Update: video of codes: