What would cause the car to suddenly start running on 3 cylinders?

I just purchased the car and I was on my way home. After only 6-7 miles the "check engine" light came on. It stayed on solid for a couple of miles, then it started blinking. A dozen times or more, then it went solid again all the way home, a distance of 22 miles total. The engine ran perfect and smooth until the 12-mile mark and then suddenly after slowing and making a right-hand turn it started running on only 3 cylinders the remaining 10 miles home. Once along the way I stopped, turned the car off, waited a minute, started back up and continued. It remained as a 3-cylinder. After letting it sit and cool for an hour it still runs on only 3. Suggestions?

Thanks