My 02 chevy cavi has erradic idle going from 500RPM to 1000 only while at

[skipper]

complete stop, could be alternator? I have a 1200watt amp going to my speakers, but I installed a capacitor in it. Anyways, I was driving the other day, when the stereo started sounding staticy, then the speakers just didn't work, next my cars idle becomes erradic only at a complete stop. It drives normally, but when i stop. Could this be the alternator? I have never replaced it, and I have driven about 70,000 miles on it. I replaced the fuel filter last year, and also the fuel pump. I also am cleaning the air filter and the Idle air control valve. Tomorrow, I will remove the alternator to have it tested. Please no smart ass comments like "Should have bought a ford" Cause right about now, I think I should have. Thanks