Starts fine, then dies while idling

Truck started doing this a few weeks ago. It happens occasionally. I start the truck, let it idle for a few seconds, put it in gear and while coasting, (no pressure on the pedal) the truck will sputter and die. Sometimes it fires right back up and is fine, other times it takes a little throttle work to get it started. What do you guys think it is? It happens in the morning after the truck has set for awhile. I would say it occurs about 1 out of 4 mornings that it is started. Fuel filter has about 6k miles on it.