What would cause engine to stop unexpectedly?

Water buildup in the gas tank,causeing fizing in the fuel lines.Octain is important to a combustion engine,there has to be anough explosive energy.If theres an abundent of water excess,the engine cant conbust properly,there for causeing stalling. Clean your gas tank out.Put omly high octain fuel,even had octain booster your car will combust and run smooth.