1). Connect Fluke scanner to 16 pin OBD2 port. (1 minute)
2). Read #4 misfire code
OBDII Code P0304 - Cylinder 4 Misfire Detected | HelpForCars.net (1 minute)
3). Read O2 sensor code
OBD-II Trouble Code: P0133 Oxygen Sensor Circuit Slow Response (Bank1, Sensor1) (1 minute)
4). Notice on the pretty little digital graph display that the sparkline is flat on that cylinder. (1 minute)
4 minute diagnosis tops. Ask for your money back.