Dodge Ram 1500 2004 trouble code P0308

I have twice now gotten code P 0308, have looked it up and understand it. My question is what is causeing it? I have owned the truck since it had 10 miles on it. Does it simply need a tune-up or something more? It now has 57000 miles on it and the sparkplugs have never been changed so....... just looking for suggestions and insight.

It could be just a tune up but again we aren't there you are so if you understand the code then take the info from this site and perform the diagnosis and/or repair or seek a professional. We can't see it , hear it or feel how it runs, look at the data etc so it could be a tune up, could also be a hole in the piston, bad valve spring, defective fuel injector, slipped rocker, ignition problem, headgasket etc, etc etc, We gurantee nothing here except free info and some advice. We can't confirm what's causing it. How would we from here?