Hey guys, could really use some help here. I have a 2006 5.4L XLT 4x4. A few months ago I had the missing, sputtering, etc. everyone experiences around 100,000 miles. ( I now have around 105k). Anyway, I changed my fuel filter, air filter, spark plugs, and COP's. Truck ran great. Now, all of a sudden, I am having the same issue. On the highway at crusing speed, it will periodically miss. Almost feels like hitting a pot hole. And its getting worse. Anyone have this same issue or know what I could do to fix it?

 

Scan for codes, misfire codes can and will be stored and not necessarily turn the check engine light on. Sounds like one or more of those new COP's are defective or you cracked the ceramic insulator on the plugs during install. Short of that maybe a worn out injector.

 

plug wires. they can be bad right out of the box or go bad in short order. copper wires won't go bad but you won't be able to listen to the radio. good luck

 

we don't have plug wire...but thanks anyways..

 

Check the condition of your FPDM located under your spare tire mounted to the frame rail... they corrode and cause problems just like your describing...

 

Went with the same problem on my 2006 F150 King Ranch...going at 40-50 up a slight incline and it would sputter or "miss"... My mechanic put this in my truck and we are driving it for a few weeks to see if it does the trick. He said if you do not get a check engine light and it is not burned out, it is most likely not coil, plug or wires...
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