engine died while driving, won't turn over.

[Retroman1969]

I'm no expert, and really hope that I'm wrong, but I've read a lot about this issue over the years, and it sounds like a textbook description of an IMS failure.
They can go without warning, without noise, and over half the people I've heard about that had the failure had it when they were stopped or coming to a stop.
178,000 is pretty mature for any car, but especially one of these.

Best of luck on this. I hope it turns out to be something trivial.