Trying to figure out what is going on with my friends car. It is a 2010 Gulf TDI manual transmission with the emissions fix installed. He has always had this symptom that intermittently occurs between 1800-2000RPM at moderate loads. Doesn't matter wether it is at highway speeds or slowly driving around town. There are no stored DTC's. I haven't observed anything that stands out when the stuttering is happening and watching live data. Has anyone found a permanent repair for this? The local dealership is only good at one thing.. taking money with no sign of action.

Thanks in advance.