Originally Posted by 1slow370

no he means the blow off valve looking thing could be open when it isn't supposed to be, on the supercharged cars i believe the norm is that it is supposed to be open under idle though to allow the excess air to recirculate. the idle is most likely an issue with the maf curve, when they tuned your car for WOT they mostlikely adjusted the k value to bring the ecu closer to the afr targets and never went back in and tweaked the maf values below 2 volts to get the idle back.

EDIT: if it was slipping already don't drive it and get the transmission tables tuned ASAP!!