Mine was doing this too, Panic stop I would have to side step the brakes and gas to keep running. Brake Booster? hmmm I need to check this for a leak. If it needs a Float adjustment it can also do this according to Weber. The force of the "G"s putting on brakes they said can cause float bowl to pour over edge and flood out carb. I adjusted floats on my Weber, which one float was tweeked down farther then other about 2-3mm. I have yet to try the float fix because i'm still doing list repairing.