My 2002 Ford Ranger, 3.0L V-6, is giving me a Check Engine light. I had it checked and cleared at the local parts store. Their analyzer says "intermittent miss on cylinder number 4." Strange to me. I certainly don't feel it. Runs very smooth. I'd been on a 1,400 mile drive and was forced to refill with 10% ethanol gas since I was too far from any non-ethanol station. Probably not related, but the Check Engine light came on shortly after the refill. I've run through a tank of decent gas and had the error cleared but the Check Engine light came back on in a few miles of driving. The spark plugs, ignition wires (Motorcraft), coil pack (Motorcraft), and cam synchronizer (Motorcraft) are not that old or that many miles - maybe 10,000 at the most. I haven't pulled a plug yet (new snow) but am wondering where to look.