Did you check the seating in the spark plugs? I had a car once that blew a head gasket, and had dripped oil into one of my spark plugs. Consequently it had unseated one of the spark plugs, and when i would slow down and make uturns it would stall out (this was an automatic my first an only), so obviously should not be stalling.
Anyway when i checked i found that, cleaned the plug and housing, plugged it back in, and voila, never stalled out again.
Hopefully just got some mud or gook up there and thats whats happening to you too. Good luck!