I'm driving a 2000 Ford Focus (Automatic/4 cylindar), and recently the engine light came on. Shortly after, the car began chugging at slow speeds, and cut out once when I was trying to back out of a spot. It only seems to " chug" when driving under 20 mph. When I move up in speed, the chugging goes away, but the engine light begins to blink. Any suggestions to fix?