[Gunn]

Sorry I completely forgot to update this post, and I hate when I find searches of interest that end just like this one did without a solution!

So yes I did find the solution. It turned out to be the simple O2 sensor (P0037 "HO2S Bank 1 Sensor 2" as reported on 11/13/2019 in my last post before this one), located down low on the passenger side exhaust pipe, right under the car. Once we (my daughter and I) changed it, we've never seen the problem since, nearly 2 years later.

How did I figure this out? Well, each time the car would act up and shut off at speed, there would be numerous check engine light codes thrown. I figured most of it was just side effects of the root cause. Each time, I'd take not of the errors and clear them. Then I would hook up my OBD2 scanner even after the car ran fine. I noticed that one of the common items in the list was this O2 sensor. So that's why we replaced it.

I hope you figured out the very same thing, since it's been eight months since you reported the very same problem. Please share if you can what fixed it for you. It would be nice to get verification that it is indeed the O2 sensor, of get info on what else may be causing the same symptoms, for the next guy, or even if it happens again.

Knock on wood...