Stalls at signals and whenever traffic is slow, typically when the A/C is on?

Hi there,
I have been facing an issue while driving: my car stalls at signals and whenever traffic is slow. This usually happens when the A/C is on. I have replaced many parts, but the issue still persists. I saw a post where you mentioned replacing the electrical system. Can you be more specific, sir? It's a big headache when the car stalls at big roundabouts. I hope you can advise.