My 1995 ford f-150 truck stalled the other day and wouldnt start. After letting it sit for 5 minutes, it started and I drove it 500 ft. Then it stalled again and wouldnt start so I had it towed. About 3 hours later I tried starting it again, and it started but only ran for 10 seconds before it stalled and wouldnt start again. I tried again after about 5 hours, and it starts and runs fine now. Why is it so unpredictable, and what is wrong with it? The truck is the 4.9 liter inline 6 cylinder, and I have never had any mechanical problems before this. However, it is getting up there with 180,000 miles.