missfire

2000 beetle auto with 145k miles. New parts as listed-- Battery -3 months Alternator -2 weeks Ignition Coil -1 day Spark plugs -1 day Spark plug wires -1 day Air filter2 weeks -2 weeks Oil/ Oil Filter -1 week Cataytic converter -1 day Code p0301 p0303 Missfire cylinder 1 and 3. Checked...