Stalling

Help-My 99 A4T is intermittently stalling when I come to a stop or slow to make a turn. It will act as though it will stall and then have no power, I have to pull over to the side of the road when it eventually stalls. Then when I restart it seems to be fine. Unfortunately it happens when I pull into traffic and boom there is nothing under my foot. Dealer says it should be acting up when they put it on the computer but I can't seem to duplicate this. It now happens at least once everytime I take it out for drive. Help??