Stalling at 65mph!!

Last week on the way home from work my recently purchased 200 Sebring convertible stalled while going 65 mph. I was able to pull over to the side of the road. Put it in park and restarted it right back up. Travelled about another mile and the same thing occured. It happened a total of 3 times in one trip. This has been going on for a few days now. Anyone have any ideas what it could be? Diagnostics turned up nothing. No codes, nothing. Help Please!!

Update:
I failed to mentioned that it was stalling after almost a week and a half of raining. This weekend it was nice out and no stalling whatsoever.
However, this morning,.. we had a rainy night and it "putter" a bit going around 65 mph. Could something be getting moisture in it and causes the "putter" and stalling"? If so, what?