If you want to know about the flutter, quite a few cars use the wasted spark system, and what happens is the coil starts to break down and instead of producing 90k volts they produce only 50k-70k and you do not get a clean burn. Due to the fact that the cylender needing the spark has preasure and fuel mixed in, raising the resistance between contact points on sparkplug. Mix this with the fact that power takes the 'path of least resistance', well the plug you need to fire dosen't, the other one does.