I have 05 F-150 4x4 4.6 litre 171 k has some vibration or engine rock at idle and 1700 thru 1950 changed plugs, belt, oil, fuel filter,put injector cleaner thru it, as engine gets warmer no check engine light comes on and the symptoms get worse any ideas?

 

If you feel at the back of the exhaust pipe you should not feel a popping, if you do there is a misfire taking place. Possibility of coil going bad.

 

I bought one new coil from Ford and here is what happened I changed pass. side front first restarted, engine light came on is all, ran it till warm no change ,etc on that side the rear boot was separated so I left in there and symptoms got worse. I'm having diagnostic done monday morning will report back thx for comments I hope it's not something serious . Ford owners need to know for the future. OK took to ford dealer monday after 5.5hrs of waiting has been diagnosed as having valve guide problem. So if your thinking about a ford have it checked out thru and thru