GILIAS

Hello Folks, I need some advice. So my 2017 Sierra 6.2 started to shake at idle just a bit, not to bad but noticeable. I took it to my mechanic and did a live scan. He noticed that #3 and #5 were misfiring but only at idle. When i gave it gas no misfires were detected. He also told me that my truck has a special warranty for the fuel system so i took it to the dealership. They swapped out the injectors on #3 and #5 and said if that didn't help then more than likely i had a bad lifter. The lifters are not covered as i have 83000 miles. So what do i do at this point? Engine runs great and i don't hear an noise coming from the engine. Please advise.