Hey, This morning when I started my 17 duramax I was startled by the engine RPM gently cycling up and down ata about a two second frequency. I immediately fired up my Bluetooth ODB reader but there were no trouble codes. It cycled like this without interruption until I briefly gave it a bit more fuel and then it stopped. I have not had this happen before. It was a bit cooler this morning but still above 60. A subsequent restart did not produce the problem. Has anyone else experienced this? I'm wondering if it might be due to some bad diesel.