Last weekend I experienced a phenomena that my wife has described in the past but I'd never noticed/felt/been lucky enough to be in the car when it happened.

Apparently when the car has been sitting overnight and is cold she will back it out of the driveway, shift into gear to drive away.  The instant it shifts into second gear, the engine bogs hard, like it just ran out of fuel.  The car only does this once, and only after sitting over night.  It doesn't do it when she's backing up, or when she first hits the throttle to drive away after shifting into drive.

Any thoughts on what might be causing this?

you could scan for a pending code after it happens.

does it feel like an engine thing, or trans? maybe shift the trans manually to try to determine?

Testing it would be difficult, as it's a one-shot sort of deal.  I drive her car often enough that I would notice it immediately, but I've only really noticed it the one time.

It feels like a temporary fuel cut, to be honest.  Accelerating away from our driveway the car will just bog really hard for a second or two, then bounce back like nothing happened.

@GeneralDisorder Every seen/heard of this?

more likely on moist/damp mornings?

any oil on plug wire boots?"

No on both questions.  Hadn't rained in weeks when I drove/felt the issue and I have inspected the oil level the day before and didn't notice any top-end oil leaks at the time.

I don't recall a complaint like that. Probably going to have to monitor live data through the event and see if you can spot an abnormality. 

You should probably look over the live data anyway. Something might show as abnormal even during normal operation. I just had an 08 Imp come in for stalling and low idle. No check engine lights. Symptoms for two months. Been to several other shops. Live data showed +25 to +30 long term fuel trims. Traced it to a bad aftermarket PCV valve installed by a shop during a "tune up". Why it didn't throw a P0171 is beyond me, but it didn't. Just stalled and low idled for two months. Drove the guy nuts. He drove an hour to see me. Went home happy. 

GD

OK, I'll hook up the SSM2 and see what she tells me.