I have had my Ecoboost mustang for 9 months now in the last 3 month I have burned out 2 spark plugs. My car is still under warranty so I took it in and they yelled at me bc they said it went out going 120 and next time they won't fix it for free. I know there is more going on then it going out by speed. Anyone else have this problem or heard of anyone having this problem? What would be causing this?