Yeah, for a food stop, I would go with one of the following options:
-Pork Pit in Mo Bay
-Cousins Cove Jerk Hut in Green Island
-Bigga's in Green Island (my top choice)

Another idea with that much time to kill would be a excursion in the Mo Bay area. That way you can have an adventure prior to getting to Negril and you would not have to lose time on an excursion later in the trip:
-Zipline
-Tubing
-Rockland Bird Sanctuary