my car used to do that, it was the a/c compressor clutch went out in it. i could have the car idling fine with the a/c
off, and then turn the a/c on, and it would studder and shut off. i think it might be your a/c compressor. your car doesn't
die any other time, just at idle/slow speeds with the a/c on? the compressor would be my best guess. O0