05 F250 5.4L 3 valve with 115k miles on it. Truck seems to stutter and miss a little bit but more at the higher RPMs. CEL does not stay on. I bought the truck used and fear that it could be the spark plugs need replaced. Fuel filter, air filter, are new, and throttle body has recently been cleaned. What are the symptoms of spark plugs on there way out on the newer 5.4ls?

 

Bad plugs or COPs would be my guess.

 

It probably still has the original plugs in it. The factory cops on the 3v seldom go bad.

 

Blinking CEL usually means the truck is running in a condition which can damage the cat. I assume its running very rich when under acceleration

 

Blinking CEL is usually indication of a misfire, definitely sounds like plugs, it probably still has the originals in it.