There is a product called ScanGauge II that plugs into the OBD port and reads most of the outputs available from the computer. You can go through their online docs and find out what parameters can be displayed for an Explorer. IIRC, it can do both real-time display and data logging over time.
I haven't looked in a while, but either Autozone or Advanced Auto Parts used to carry the ScanGauge II in the stores. Of course its also available online, and may have a cheaper price.
Bruce