We have a 2007 with a 4.6 in it. with only 97000 miles on it. plugs are suppose to be for 100,000. We take care of our vehicles. It all of a sudden started running rough. Thought it was a sensor. Took it to a mechanic. Nope couldn't be so lucky. The #3 cylinder, the plug was burnt and broke off. Now the cylinder is bad. I was told I have to replace the whole motor. Makes me mad. We went and bought a 2011 F-150 with a 5.0. Freaking LOVE it... I will never buy another truck with a 4.6. So now we are in the hunt for a motor.