1999 F150 5.4

I have a 99 F150 5.4 triton supercab 49000 miles. This has happened twice now, I'll drive it around doesn't matter if its 40 miles or just around town shut it off and I will go out 10 to 20 minutes later and try to start it and it wont start( it starts but just chugs for about 10 seconds and then dies then when I try to start it again it just turns over) the last time this happened it sat for a couple of hours and I tried it again and it started just fine like nothing ever happened. And it ran great up until today when I drove 40 miles parked it and came out 10 min later and chugged and died. Now 3 hours later and it just turns over and wont fire. Any help would be great.