UglyRed86

i have an 86 Camaro and my biggest problem so far has been the battery gauge going from 13 ( or normal stance) down to almost zero. The car shuts off whenever i am at a stop light, on some days i dont have a problem with the gauge--it is usually at 13 on normal days but sometimes it drops when i am at a stop. I recently changed the plugs and wires myself and it got worse, i also changed the air filter and the PCV valve, and i am not so sure what the problem can be!. Please guide throught this cause i have no idea what is wrong here......thanx !!!