Last time I had a truck just stop running with no warning it was the computer (ford Bronco). If you didn't have any prior indications (lights/gauges) and didn't have any audible warnings (mechanical engine noise) I would suspect electrical. check all your connectors first, if you don't find anything obvious it might be the computer. My junkyard let me test and check one i.e. I borrowed it, plugged it in, and when it worked I bought it. No guarantees but it's something to look at before you turn it over to a rip-off artist a.k.a. repair shop.