tune or something else wrong
Otherwise either you have a small vacuum leak or the tune might just need some adjustments to the idle airflow tables in the colder engine sections.
The idle hang issue is one I too am still working on, but mine only does it sometimes, not consistent. Most times it works perfect but it seems to hang like yours after I have been driving at highway speed for a while.
If you bring the car to College Station I'll look at the tune for free and let you know if I think its in the tune.

