Thanks guys! This was very helpful. My car started running rough when I started it today and immediately it felt like a coil/electrical part issue since it ran fine last night. The usual increased emissions light came on and was blinking. When I scanned my car(which I keep in the car now) it came up with a cylinder #4 misfire which leads me back to my original theory. I am just going to start with replacing the one coil for now and see how long the rest last. The car only has 43,000 miles on it now so I don't really want to change the spark plugs until at least 50,000 unless I need to.