There is a service bulletin for this issue: #PIP4112R

Recommendations / InstructionsBoth of the above conditions are a result of Torque Management and both of these conditions should be considered normal and no repairs should be attempted.
Please follow this diagnostic or repair process thoroughly and complete each step.
If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

If you are getting an engine light, download the trouble code. Some auto parts stores will do this for free. With a trouble code, you can narrow down the issue to a particular part or system.

If no engine code, it could be the issue related to the service bulletin. When the engine is geared down through the transmission, the torque is multiplied. It seems like GM has intentionally reduced torque with the Engine Control Module at low speeds to prevent damage to the drive line. There is a diagnostic procedure to check if everything is normal. Unfortunately, if there is no improvements after the diagnostic procedure, then GM considers this stutter a normal condition.