stock CAI? Stock hood? Turbulence around the MAF sensor can cause this sort of behavior, which can be a result of air blowing directly on the filter (ie aftermarket CAI with vented hood). If not, follow the advice here and clean the MAF with MAF cleaner and then clean the TB thoroughly.
Sold: 2006 GT Premium Vert, 5 spd, Tungsten Grey
New toy: 2001 Porshe Boxster S