I would focus on the cylinder that threw the code, #6. Do the coil on that one.
Doesn't take long to do and is really, realy easy compared to the older engines, everything is in easy reach of a 10mm socket, spark plug socket and an extension to reach in there. The coils are circled in red above and once you undo the 10mm bolt to the cylinder head they just slide right out. The plugs are underneath.
First time budget about 2-2 1/2 hours for the whole project. The hardest part will be unplugging the electrical connectors to get in there...they can be hard to get apart sometimes (just need to depress catch and unplug).
I also bought some spark plug boot dielectric grease (non-conducting) to help seal the boots to the plugs...use just a light coating on the inside of the end of the boot/wire. I used a q-tip to apply. Also used an anti-seize on the spark plug threads to make them easier to get out again.
Here's a good info link I found when doing mine:
http://wiki.answers.com/Q/How_do_you_ta ... Pathfinder
I just changed my plugs yesterday, and this is from memory: Be sure the engine is cool.
Remove silver engine cover (3 10mm nuts/bolts)
Passenger side: 1)Disconnect wire harnesses (2) that are held to a bracket at the rear side of intake runners. These harness are disconnected by pushing the colored tab inward (there is an arrow show that). 2)Disconnect harness plugs (2) from bracket 3)Remove bracket bolts(2 10mm bolts) 4)Remove similar bracket near the front side of intake runners 5)You should now have access to the three coil packs mounted in the middle the valve cover. Each is a small grey block with a connector attached to it, with the block held to the valve cover with a 10mm bolt. The front coil is different thant the other two. 6)Remove the 10mm bolts holdin the coils to the valve cover. 7)Lift the coil straight out,and disconnect the cable attached too the coil. The connector disconnects by squeezing a locking tab on the side of the connector. 8)The spark plugs are now accessible.
Driver side: 1)Remove black plastic air tube that goes from engine (throttle body) to air filter housing (6 clamps) 2)On the middle coil pack, you should see that there is an electrical piece on the throttle body that will prevent the coil pack from being removed. Remove the two screws that hold the part to the throttle body, and move the part out of the way (no need to disconnect it electrically) 3)There is also a wire harness bracket below the middle coil pack that has to be moved out of the way. It is held to the valve cover with one 10mm bolt 4)You should now have access to all three coils packs. Remove as explain in the passenger side section. 5)The spark plugs are now accessible.
Here's a picture of that electrical sensor in the way of the middle coil. You just need to unscrew and move out of the way... I found that a short phillips head screwdriver helps to reach in there. And since the throttle body is right there (silver tube center of pic) you can give that a quick wipe clean too...