keepitupguys

I am a lifelong GM truck and tahoe/burban owner and am losing my mind on this issue. we have had a variety of them for our multi location small business, not exactly a fleet operation but have had enough trucks to know when issues start to present themselves. I'm on the road with regular towing and loading, 500-700 miles a week on my daily driver which isn't the most in the world but isn't nothing, mostly two and four lane highway miles, weekend gravel and dirt use in the upper midwest so a lot of four wheel drive all winter. My last daily driver was 2016 Tahoe 5.3 V8 on 6 speed transmission with 3.08 gears. changed torque converter at 50k and slightly improved, changed tranny fluid again around 75k, the truck got slightly worse each time and did it until I traded it for a 2020 crew cab LTZ/Z71 Chevy with 8 speed tranny and symptoms started around 40k. Been working with the same GM certified shop for decades who found the TSB, changed the tranny fluid and gear boxes. improved slightly but getting worse gradually, replaced a front bearing for noise but now at 90k on the 2020 and just took it in today for an oil change and having the shop check it out again, the low RPM at both high and low speeds is as bad as it was at 40k. still own a 2009 HD 2500 silverado snow plow truck with 200k miles on big block V8 and never had any low RPM shake, several crew cab silverados with the 5.3 L V8 before the 2016 Tahoe and also still have a 2011 GMC yukon XL with 160,000 miles on the 5.3 V8 that has also never had this issue. It has got to be something they've been using just these last two generations.