I have a 2016 Equinox LT that I recently bought from a dealership and it has an electrical issue.
It seems fine when I first start it but after it warms up and runs about 15 minutes, it seems to "reset" on medium or heavy acceleration.

It seems to happen when you'd expect it to be shifting from first to second. (It also does it at higher speeds when it should be shifting)

Normally, it shifts completely smooth. Not when it's acting up it shudders, the doors unlock, all power shuts down, then within about a second everything turns back on and it acts like everything is fine.

Has anyone seen this before? I'm guessing it's either a bad ground or a bad ECM.

 

Could be a bad ground.
make sure your electrical connections under the hood are clean and tight.
a janky ignitions switch might do that too.