Ya'll will have to excuse my lack of knowledge on the powerstroke. This is my first one. Just got this '08 6.4L and love it so far. After driving around for a couple hours I pulled into the driveway and just as I turned the key to shut it down, I noticed the RPMs were climbing, like a high idle or something. As I said, I noticed it AS I was shutting the key off. I restarted it and it idled fine. Can anyone tell me what this might have been???