was it idling REALLY low? i think my O2 sensor is bad b/c it doesnt like to start up when it sits for a while(btw does that sound like thats the problem?) and when i do get it started up it idles really low... after i let it sit for a while and start driving it it will buck back and forth also and then i hold the pedal down and it finally pulls out of it... see what happens if you do that... my car drives fine after that... as far as the sound goes mine makes the same sound right before it dies but i always attributed that to the RPM's being extremly low or something
-Josh