Vibration at Idle!!???

Hey, so I have been having a issue with my 06 5.9 CR auto trans, for a while now. It vibrates at idle, ill try to discribe it it idles kinda "shakes" then goes away for a second then does it again and will keep doing it. If the engine is slowly reved up too 1100 rpm it will keep doing it but faster and faster till 1100 rpm then it will stop and it wont do it anymore after that rpm. A new CP3 was put in not long ago but it did do it before that as well. I do have EFI Live. Im not sure what it would be. The truck does it 99% of the time, the odd time it wont do it but not often. Doesnt matter if the engine is cold or hot. Also this is only if the truck is in Park will not do it in anyother gears.