SVT running weird

so lately my svt has been a little deeper in sound. when i am coming to stop and leave it in gear it makes a Blub Blub Blub sound that i havent heard, and i do have borla exhaust(but that is not the sound, i know that). when i am sitting at idle and start to move, then stop, it sometimes dies.
i was in the parking lot at my school and was moving about 15mph then put in the clutch, put it in neutral, let the clutch out and hit the brakes. when i came to a stop my engine died. happened 3 times today... any ideas? alternator? wires? dunno. help me please