Jerome Leberer

Hey guys and gals, Long time creeper, first time poster. I currently have a 2011 silverado 1500, with 163,622 miles on it. It's a 5.3 vortec engine. It smokes from the exhaust a light blue exhaust that's mixed with a grey/white exhaust. It stops smoking after roughly 10 seconds of running. Haven't noticed it while driving. It also doesn't smoke every start-up. It rough idles when in park. I replaced the plugs and wires a couple weeks ago, and I started misfiring on cylinder 8 after the change, before the change it was cylinder 5. The only codes it's thrown is for the misfiring. I also pulled plug 8 after the codes to check it and found oil on it. I did a combustion gas leak test and the liquid stayed the same color (blue). I'm starting to lose my mind. Any thoughts, suggestions to try? Also, as of now....I've noticed no loss in power at the moment.