I have had the same issue with coil packs before and just replaced them all and problem solved. (misfire you could hear and sort of feel, yet no codes)Only reason I’m looking at em now if because I have this weird random misfire that don’t throw any codes and is usually low in the rpm range and at idle it just is running rough. I did plugs last time I was home I’m waiting on my new wires to come in the mail and I was going to replace the coils because I bet one of them is bad @400,000 miles just about now… its almost like a spark knock but a misfire if you know what that sounds like on these 5.3s
I know I’ll probably not gain any real performance gains but as long as they last like the factory ones have I’ll be happy. Last time I got coil packs I got the eBay special cheapest they had and they burned up within 6 months and I swapped back to stock ones from the scrap yard
Herko sells on ebay but atleast there stuff is oem, even though it may come in a herko box. they do sell some other brands but for oem the price is good
there prices are pretty hard to beat for oem coils, injectors, fuel pumps
website: https://herko.com/search
on ebay: https://www.ebay.com/str/eherko