I have a 2018 GMC 1500 5.3L with the 8L90 transmission, the truck has 77,000 miles on it and I just bought it but I’m no when I’m coming up to a stoplight or when I let off the gas pedal at lower speeds, it feels as if the brakes are engaging in the truck does a small jerk and the RPMs shoot up from one to two and back before stopping. It doesn’t feel like much as the transmission runs perfect at all other speeds no slipping or anything. Just not sure if this is normal or something. I should be concerned about. I also have the AFM disabler installed as well.
