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Did you get a check engine light on and/or have you had it scanned for stored fault codes? Do you have any modifications to the vehicle and have you had your air and fuel filters changed any time in the recent past?
There is likely a type B fault code stored which requires two failures to set the light on. I would recommend you have it scanned for any faults that may be stored initially. As simple as it sounds, fuel and air filters are by far the most common cause of this concern on the duramax. Huge amounts of air go through the engine and they are much more sensitive to restrictions in the air filter and fuel filters than any gasoline engine. Probably 85% or the concerns I've had with these have been fuel and air filters. I would recommend changing both, having it scanned and clearing any stored faults and if there are any, reply here. I know it sounds so very basic but believe me it is the most common cause of this concern.