2011 Equinox Dies a Few Seconds After it Goes Closed Loop

I'm helping a friend with a 2011 Equinox that dies on cold starts a few seconds after going into closed loop.
It's not modified or anything.
Only seems to do it when cold.
Colder ambient temps make it worse.
Once you restart it, it's fine for the rest of the day.
On warmer days (above 55*-ish), it will stumble but not die.
If you take-off and drive it before it goes into closed loop, it will hesitate and lose power right after it switches to closed loop, but doesn't die because of the off-idle throttle position.

It seems to be caused by the ECM commanding short term fuel to -20% (or even more lean) a few seconds after it goes into closed loop.
I don't know why the ECM is commanding -20% on the short terms though.
If I disconnect the MAF sensor, it won't do it.

The upstream O2 is fairly new as I replaced it at the same time that I replaced the exhaust manifold for being cracked (about 8 months ago).
I tried swapping to a new MAF sensor, and it didn't help.

Any ideas what's causing it to command the short term so low?
I'll attach a log.