I am not familiar with what's in the 97 - could you tell me what the set up looks like?
Are you getting any mid-range? Unless you have an actual bass box your mid-range and bass come from the same cone. If you have no mid-range then the amps may be dead.
If you have the Mach system there are 3 factory amps. One drives the tweeters, and the other two drive the 4 woofers. If the tweeters are the only speakers playing I would check fuses. I think the fuses for the amps are in the fuse box under the hood, not the one under the dash. If you cant find any blown fuses I would assume that there is a problem the the factory amps and you will need to start repalcing equipment.