Can't answer some of this, because our 2.3 does not have an 'economy' gauge. Still, the CIS injection IS designed to shut off fuel thru the injectors in most deceleration conditions. With your foot off the accelerator, engine braking would be normal.
My understanding is that the function of the microswitch behind the accelerator linkage, above the throttle body, is the one that provides the ECU with the decel fuel-cutoff signal. The ECU also balances this against engine speed and possibly other factors.