Don't Throw Away Those Old Spark Plugs, We Can Fix Em'... AND, I Need Help From The LS Crew!

I've been dealing with a minor stumble at idle and poor fuel mileage in my daily driver, a 2009 GMC Sierra, for the past few months; I decided to try swapping spark plugs and wires to see if I can manage an easy fix for once. Well... The easy fix didn't come to fruition, but we did learn something about high performance spark plug wires that I didn't expect, not really sure how it impacts performance in general, especially when talking about tens of thousands of volts generated by todays powerful coil systems, but interesting information regardless and I'd love to hear what you guys think. We also ran the old AC Delco spark plugs through my Sunex Spark Plug Cleaner, with great results. With the quality of aftermarket parts these days, holding onto these older, good quality plugs might prove to pay dividends down the road. Would you guys use these in your daily? Check out the video and let me know what you guys think. Am I being too hard on the ole' 5.3? I kinda feel like if I'm gonna deal deal with 13 MPG, I should at least get to have some chop right?? Maybe its time for a cam and a carb? LOL LS experts, tell me what I should do next? Is the stumbling idle a rich/lean symptom or timing issue?