Cooling issue, but this time it's to cold...

Maybe the stat is just too slow to close? But two in a row? IDK..... It's job is to control the minimum operating temp. It doesn't seem to be doing that.....

I'll tell you what I would do.
I would take the radcap off, and bring the engine up to temp at a stand-still. I would clamp the top radhose off, say 80%, put the cap back on, and take it for a spin.
If the temp goes up to overheat, remove the clamp, and let her cool off. Conclusion; bad stat.
If the temp goes down, conclusion; That's gotta be impossible. But if it does, that takes me back to my first post.
That's what I would do.