There came out of my sisters Nissan Xterra and they were supposed to have been changed out with a complete service a while back. OBVIOUSLY they were not! I would bet that these are probably the original plugs. A couple of the plugs needed to be extracted with some tricky extensions and swivel joints. This is because the intake manifold goes right over them but with the right tools you can take them out working blind and by feel. The stealership simply didn't want to have a technician spend the time needed to do this.
The truck was running rough and I decided to just do it all; plugs, wires, cap/rotor really check things over. You can bet that the gap had something to do with it, let alone the deteriorated electrodes.
Don't even bother trying to get more power out of your engine if you are neglecting simple things like your air filter and spark plugs/cap and rotor.