Hello,
I have an 08 6.7. I have been noticing that when I'm in drive and I let off the throttle and when the rpms hit idle it will rev up slightly, like 50-100 rpms then drop back to idle rpm. Its most noticeable at low speeds when I let off and it drops immediately to idle vs highway speeds when it takes a bit to drop. Anyone else seen this?

 

mine does it to, even in reverse. nature of the beast.