What happen after change out the news battery then the idle stalls?

After changing out the battery, if the vehicle stalls at idle, it could indicate several issues. The new battery may not be properly connected, leading to electrical problems. Additionally, the stalling could be caused by a vacuum leak, fuel delivery issues, or problems with the ignition system that were not related to the battery. It's advisable to check all connections and conduct a diagnostic to identify the root cause.