Yes, there is a one to two second delay before the fuel shuts off after the throttle in closed, which appears to be programmed into the ECU.

I believe it is there to prevent jerking if you are just feathering the throttle. Also, for the fuel to shut off, both the TPS and linkage microswitch must be in the right position, which I think is closed for the microswitch and open for the TPS.

Duke