It has old plugs. It has 206,000 miles on it. I've never changed the plugs myself. Whatever it is, it happened within a 10-20 minute period. It was running fine at one stop sign and it wasn't at the next traffic light. If it is a plug problem, it would have to be something like a cracked ceramic. A coil wire can break inside the potting and give a weird/weak/intermittent contact and that would happen quickly. Of course I have all sorts of free time this week, so it's a perfect time for this to happen (not).