I just had the alternator replaced because my car died on me yesterday. It runs fine now but, sometimes when I stop it idles a bit too low, around 500-600 rpms. Before I had the alternator replaced it would be at 750 to 1000 RPMs. I've checked the battery and it perfectly good. Can anyone help me out and tell me why this might be happening? It makes this weird kind of jerking motion randomly, almost like it about to shut off completely but, then it keeps running. It was doing this exact same thing right before the alternator went bad. It died on me a few times at a complete stop so I don't want to keep driving it like this until i have this problem solved.

P.S. I have an automatic D16Y8 with vtec

 

Maybe, just maybe you want to check teh tension of the belt.