I’ve replace both banks of injectors in 2016 Yukon 6.2L due to throwing code. When they put the one side of injectors back in, the idle still had a stubble. I was always told it was normal and figured as such but one of thier “heavy techs” did some more tests and it ended up being the cam/lifters. Those items were repaired under warranty. The injectors are not covered....sigh. Once the cam lifters were replaced, the 6.2 purrs.
if you can’t diagnose your idle stubble, look at cam/lifters or have your tech investigate.