2000 Ford Ranger stalling out

Engine Mechanical problem
2000 Ford Ranger Two Wheel Drive Automatic

I have a 2000 ranger with 79000 miles on it. This problem keeps happening to me where I start my truck after it has been sitting for a few minutes it idles about 500 rpm and stalls. The problem only happens when the truck is warm. Once it has had time to cool down the truck will start and idle normally. The problem has happened twice now. Last time I replaced all of the plugs and wires as well as cleaned all of the censors, this seemed to do the job until the second time. Any clues