The computer module (PCM - Powertrain Control Module, sometimes also called ECM - Engine Control Module) on a 1998 Ford Explorer Sport is typically located
under the hood, near the passenger side fender well. It's often attached to the inner fender apron or secured to a nearby support bracket. It's a relatively large, rectangular black box with various connectors.
However, precise location can vary slightly depending on specific options and trim level. It's best to consult a 1998 Ford Explorer Sport repair manual or use a reliable online repair database (like Mitchell OnDemand or AllData) with your vehicle's VIN to get a definitive location. These resources will usually have diagrams showing the module's position.