Could be one thing, or a combination of many - Not a "normal" driving pattern as mentioned - and not uncommon in the particular circumstances.
As amc mentioned, the engine is slowing fast and tends to keep doing so in this circumstance. It's got ONE chance to "catch" before continuing to a stop, and the slightest "misfire" for example would be enough that it dies at that point.
Plugs/boots not quite perfect, an injector a bit dirty, IAC a little slow to respond, you could chase the issue quite expensively without solving it if all possiible suggestions were followed. That's probably a major reason for a lack of suggestions to "solve" the problem.
Drive it as is, see if it does anything similar at other times, consider "tune up" type maint. if not done recently (plugs, fuel filter) and see how it goes for now.