zx3zetec -
In my Saturn, at highway speeds, the "neutral idle" RPM is higher then my normal idle. My normal idle is between 800 and 900 RPMs. At highway speeds, the idle is usually between 1000 and 1200 RPMs. We have deduced that the ECU/PCM is changing the setting of my Idle Air Control valve because it is seeing higher MPH.
As long as your coasting-in-neutral RPM is lower than your coasting-in-gear RPM, then it's a win. But, not as good as it could be,
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CarloSW2