I have a 23 Silverado, 12000 miles, with the 3.0 doing the same thing so mine cannot be AFM. I get a slight vibration or shutter when maintaining speed at around 1700-2000 rpm. Do you remember back when you drove a clutch and you shift too early and it would bog and shutter until the rpms got up, that is what I feel. Seems like torque converter shutter. I took it to my local Chevy dealer and they said they cannot replicate it. I plan to take it back in and have them ride with me to help them see the error in their ways.
