My mechanic is a bit stumped on this, I am going to take him for a ride Friday to show him what's going on. But in advance of that, I'd like some additional perspectives.
I'll take my boat out for a cruise, it'll run great, it'll idle smoothly and when I go to anchor a ways in to a no wake cove zone it will die consistently in the same spot. I would say it consistently dies about two or three minutes while idling in gear. I can reproduce it quite easily. After it dies, it will start up pretty easily.
It is a Merc 6.2 and I have a brand new IAC as well.