Hello all. My truck is a 2006 F-250 6.0l PSD. 55K miles, bone stock. I was driving it yesterday and noticed that my RPMs are fluctuating somewhat right above idle. Not alot, just barely half a line on the tach (about 50 RPM). Is this normal or a sign of things to come. Truck is under warranty yet. I have not been driving it lately, but my wife has been. Otherwise the truck runs fine. Any advice is appreciated. Thanks.