I have a 2020 1500 Limited with the 5.7. I live in San Antonio and have had the same cold start, rough idle issue. Especially recently with the temps dropping to the 50s. I have a stock air intake box, other than a K&N replacement filter. I recently put in a friction modifier into the oil and a fuel system cleaner. I also use 93 octane. I know it's not needed and won't necessarily give me any benefits. Just like using it. At just 1000 miles on the odo, I shouldn't need any of that, however, after putting it in, my cold start issue has gone away. I also removed the secondary filter / mesh that was in the stock air intake box. Not even sure why that is there. I will also try the throttle re calibration and see how that helps. Even after the additives, I still get a rough idle and the truck searches for it's idle point for about 10 seconds.