It's a great motor, but what Ray says about the spark plugs is Gospel. It's not just that the plugs last a long time, it's also because the spark plugs are fairly deeply recessed in the OHC heads and unwanted debris and moisture collect in the recess. That's the way it is on my 6.8, and I think the 5.4 is of similar construction. I didn't know about the issue when I got my 6.8 nine years ago and when I finally got around to changing the plugs it was a pain in the rump.

Brian~