NHTSA Complaint #11449446 — 2021 GMC SIERRA 1500

8 lifters in my vehicle needed to be replaced. While driving my vehicle (12/4/21), after the auto stop feature was activated my truck experienced a lack of power and hesitation. I then turned the truck off and upon starting it was making a knocking noise. I immediately checked the oil as I wanted to make sure there was oil in the engine. I had warning lights on the dashboard and drove it about 3 miles to the dealer to be repaired. While driving it to the dealer, it did not sound right and shook. I also experienced a lack of power and was concerned for the vehicle to stall out while in traffic. The dealership informed me this is an issue with the 2021 GMC Sierra with a 5.3L V8 engine. I had seen online that GMC issued a service bulletin to have the lifters replaced in the 2021 GMC Sierra that were on the lot before they were sold (early December 2021). If this is a known issue why weren't the lifters replaced in vehicles on the road before the ones sitting on the lot. 8 lifters were replaced by the dealership but there was a shortage of parts due to the nationwide problem. There were no warning lamps, messages prior to the failure. The only symptoms I had was shaking and lack of power as indicated above after the autostop feature was activated. I then drove about 2 miles and went into a store before coming out and having the loud knocking on startup followed by warning lights and messages.