Mate, its been 20 mins! Relax, someone will answer your question. The battery light always comes on when a car is about to stall. It has nothing todo with the battery, its just that the alternator isnt spinning fast enough, cos the revs are too low. Battery is fine, and you say that the car is starting fine, so I'd say the alternator would be fine as well. I dont think it would be the power steering, and possibly the idle switch. My mate had the same problem as this, and turns out the throttle body was open too much, letting in too much air, and stalling the engine. Might pay to have that one checked out. Otherwise try doing a diagnostic. Or convert it to manual
I have always been under the impression that if you can stall an auto, you're talented...
Good luck finding the problem though. Have you had a mechanic look at it?