Check to see that your MAS has the splash shield installed. Your profile says you have a stock Z but if you just bought it a week ago you may not know what's stock and what's not and if you have a pop charger air filter installed without a splash shield it can cause stalling at speed due to air turbulence.
Open the hood and remove the nose panel of the car and see if you have a round cone shaped device in there. If so, then you've got a pop charger. If you see a big plastic box looking thing then you've got the stock air filter set up.