This has happened to me a few times. Coolant temp is already warm around 120, shut off, and it stalls a short time after I restart it. Restarts fine after that. Ac is always on since installed. The most recent time i went to a car show. Car was parked three hours. Started fine then stalled at the stop sign after less than one minute. Not sure if this could be ac related. I increased iac steps for ac to 30 today based on a previous post.