OK, she's running again! Picking her up this afternoon.
Needed 2 new wheel speed sensors, which certainly would explain some of the issues and lights.
BUT, the stalling/misfiring is still a bit if a mystery. They couldn't get it running right until they flashed the ECU back to stock/took off the tune. They're not sure yet if simply resetting the ECU fixed the issues temporarily, or if the tune and/or plug gap was to blame. Clearing the codes didn't help. He suggested I give it a few days on the stock tune and stock plug gap and see if the issue comes back. If it doesn't, then we can re-visit the tune with the proper plug gap. Going to try to get more details from the tech when I pick it up.
All of it covered under the CPO warranty (minus the $50 deductible).
¯\_(ツ)_/¯