6.2 injectors can start showing issues anywhere from 60 to 90 k. The engine that had one stick open I think the guy said it had in the 70k range? DI injectors in general wear. It's high pressure "dry" fuel with small abrasive particles in it. All of the 6sp problems that people start seeing around 120 to 130 k are almost always because of the 5.3's injectors being worn. They start running with (-15ish%) trims throwing the torque models off causing lower line pressure resulting in less clutch hold pressure. Also why a new reman won't last more than another 30k in most instances when put back into these vehicles. This isn't your fault... I almost always ask for mileage when I tune one for this very reason and I just let them know up front if something looks off. If it's a higher mileage 5.3 for example and they're complaining about some TCC or shudder issues in general and I see negative trims then I know to increase the airmass torque model a little because they hardly ever want to install the injectors I've never seen a 5.3's stick unless it was just high rail pressure. On the plus side of things the 6.2 injectors can run some REALLY high rail pressures as long as it's not the LT4 6.2 injectors. The LT4's need to be kept around the same pressures as the 5.3's for whatever reason... SOooo, not your fault.