Idle Vibration

[JThacker]

I just noticed this today have never noticed it before. Let me first say while in the truck you can't feel any abnormal vibration but if you open the door and hold it you can feel a rhythmic vibration. It is so rhythmic and constant that it worries me about something internal. It also speeds up with increase in rpms but also lessens significantly so that at above 1700 you can't feel it. Likely has something to do with my dual disk clutch, I also have a fluidampr that's not in my sig. Any idea's?