Yes. The VSS drives a few important things in the Fiero. Knowing what speed you are going, and having the correct mileage reporting on the odometer are good things to have. Also, if the VSS and RPM readings don't match in the ECM, the computer will light the CEL and may end up in limp mode.
I'd reset the ECM (disconnect negative battery cable for a few minutes), and see if the problem recurs. If it does, you may need to replace the VSS itself, or the gear on it. Or there may be a wiring issue, such as the VSS wire having gotten rubbed through, and occasionally contacting ground, causing a short, and misread of the value.