HELP

I see that this problem has been mentioned a few times but I am still not sure if any one has resolved the issue.

My battery keeps dying on me, especially when I come to a stop, usually at a traffic light. The car wont start until I jump start it. I have replaced the altenator and battery, but still having issues. Now the battery light is coming on also. I also recently changed the stero which had a built in anti theft alarm. Could this be the root of the problem. I have had 3 mechanics look at and they can't find any shorts.

Any ideas would be greatly appreciated otherwise I will trade it in next week.

Thanks