Yeah when you take the boots off your coil packs to install the supersparkz, be sure to clean everything good. I took a little piece of fine grit sandpaper and sanded the electrodes to get a better connection. James says you can just put the supersparkz on and you're ready to go, and you are, but I like spending a little extra time to clean things up as best I can.
Also, go up to Advance and pick you up one of those little packets of spark plug/electrical connector grease and a pack of anti-seize. Put the anti-seize on the threads of the little bolt that holds the coil pack in, and put the electrical grease on the outside of the supersparkz so it will slide in the rubber boot easier. This grease will also help protect it from any moisture that might get trapped in there.
As far as the misfire on cyl #5, it seems that misfires are fairly common if we let our trucks sit and idle for extended periods. I wouldn't worry about a misfire on one cylinder much. When you start getting a P0300 code (random misfire) then you want to start looking at MAP/MAF sensors, coil packs, new spark plugs, etc, and hope it's not the head. People like to freak totally out when they get a P0300, but more often than not, it's something that can be corrected. My P0300 code was caused by a broken wire on my MAP sensor. I was experiencing every symptom of a bad head, running rough, etc, and I found that loose wire, fixed it, and it's never done it again.
Even bad gas or a little water in your fuel can cause a misfire code, so always make sure you're putting good quality fuel in your truck.