[MetroMPG]

Just a thought: keep in mind the zero fuel use you're observing when releasing the throttle while in neutral might be a function of the OBD-II gauge. (They don't directly monitor fuel consumption -- they monitor air consumption and estimate fuel use based on an algorithms. EG: the Scangauge's "fuel cutoff" threshold which reports zero-fuel use is actually user-adjustable.)

The surest way to confirm what you're seeing is actually happening is to directly monitor a fuel injector.