My E16S has a rough idle. It sputters hard when sitting or driving. I checked the plug wires and found one of them has corrosion built up in the connector where it plugs into the distributor. I tried to clean it out the best I could at the time and it ran much better but eventually got worse again and I found the corrosion was back. Why is the corrosion happening there and how do I stop it? I don't want to buy new wires (they're only about two months old) or a new distributor.