Im still looking into this one.
My local dealer rang Ducati's tech bod's and all they could come up with is there might be a air leek between intake/head
!!. Apparently there are a few 999 that have suffered from this problem, and from what i gather all in cold weather.
Sounds to me as if there clutching at straws. My dealer has not had the bike in yet to check it out but reading between the line's he's also under the same impresion that ducati have'nt a clue.
I'll keep you informed