2005 5.4l multiple misfire P0300 code
 

I have a 05 with 117k miles on it, and am getting a multiple misfire code. Truck runs good at idle and under normal acceleration. If you WOT throttle truck from a dead dig or from any speed it bucks and misses like crazy through the entire RPM range. Any idea what it could be? I have cleaned throttle body, new air filter, and fuel filter. Also have ran fuel cleaner through a few tanks and nothing has helped it. I was wondering if these trucks have a EGR valve on it?

prolly a coil or a coils are about due, along with spark plugs. I had my plugs changed at 60K and the gaps were worn the hell out! had to have one of my coils replaced around 57K cuz it took a dump.

I was thinking it could be some plugs but then from what I have heard if you had one or even three cylinders missing it would have shown up on the scanner. This showed a random multiple misfire code which lead me to think I have several cylinders missing.

Was the 100k tune up done on the engine? What brand of spark plug was used?

i bought the truck used, and I dont know if it has had new plugs yet.

do these motors have an EGR valve?

Seeing that you bought it used and don't know if the plugs where changed start there and change them. Then if it still doing it find the bad COP. Check to make sure there all on good to.

did you ever find out what it was? Mines doing the same thing

You asking in a 13 year old thread . What have you done so far for maintenance ?