what brand of plugs? bosch plats have a problem with fouling VERY easily. always use the same plugs mb built the car with. otherwise, you might look at the caps, rotors and wires, possibly coils. low kv-not enough spark-from the coils or caused by the other parts will look like too much fuel. i'd be interested in seeing the actual numbers from the test. could be another number is off along with the high co. good luck, chuck.