Why car stalls when you let off the gas?

A car may stall when you let off the gas due to a few reasons, including an idle speed that is set too low, a vacuum leak, or issues with the fuel system, such as a failing fuel pump or clogged filter. When you release the gas, the engine may not receive enough fuel or air to maintain the necessary RPMs, causing it to shut off. Additionally, problems with the ignition system, such as worn spark plugs, can also lead to stalling when decelerating. Regular maintenance can help prevent these issues.