Alright... the FAQ told me that I need to have an OBD-II. I have the OBD-I, so I'll take it to AutoZone so they can check it for free.
Anybody have any guesses as to what it might be? I noticed no difference in performance, no new noises, everything it routed correctly, and the car has almost 69,000 miles on it. I know it would be a stab in the dark to guess what it might be, but any possibilities would help me out.