You guys might think I am a moron. But I also had this problem. I took it to the dealer and it of course wouldnt do it while they were looking at it. I drove off and what do you know...started doing it again...so I pulled over and looked under the hood. And you know what I found? My OEM alarm horn that is mounted on the air box wasnt tight. And was rubbing up against **** in the engine compartment. I took it back to the dealer and showed them and asked them to move the horn a bit and tighten it up. They did and it quit. Mechanic said "well ill be damned...never heard of that before..." and off I went. Never had the clutch vibrations/noises again.