Happened to me in a 121 engine which suddenly stopped in the middle of the road once in a blue moon but the exact cause could not be traced for there was no stored error code. Agent recommended an overhaul (I can't blame them! It could have solved the problem anyway but left a hole in my pocket) but the fault disappeared after a throttle body/injectors/PCV/OCV filter/MAF sensor clean up and replacement of injector washers (a few cracks were visible), air filter and of course the plugs. It never