1996 Chevy S-10

While driving the truck just stopped, it would crank but would't start. I had it towed to a garage and they said it was ignition switch, there was no spark to coil. After it was replaced it ran good for about 100 miles but now it is doing the same thing. It will stop all of a sudden and wont, t start, if I let it sit for 12 hrs it will start again and run good for another 50 to 100 miles and do it again