I had an oil leak about a week ago. It was a valve cover leak and was in the front of the motor on the drivers side. The leak was fixed but ever since the leak startedthe back cylinder on the drivers side starts to miss after 5 to 10 minutes of driving. I have replaced the plug and tested the sparkplug wirewhen the cylinder is missing and the spark is strong. Just to be sure I looked at all of the other plugs and tested the other wires and everything was fine. It is just the one cylinder that is creating the problem. When the miss starts it is missing then not missing. This happens for a few minutes then the miss is constant. The engine light is on, but it was on long before this problem started.