If your Ford Focus has starting running very poorly, or stopped running entirely while showing symptoms of lacking spark, your Ford Focus ignition coil is most likely the cause.
Any time the Ford Focus ignition wires exhibits physical damage either to the ignition wire or the boots, the Ford Focus spark plug wires should be replaced as preventative maintenance.
Ford Focus Copper and Platinum Spark Plugs by Bosch, Denso and NGK. Replace the Ford Focus spark plugs once a year for optimum vehicle performance and increased fuel mileage.