I don't know if its different in the 2000 bodies but my 99 had to replace them by removing the rear seat and the carpeted deck from inside the car, screws are on the inside... kind of complicated but only took an hour of work to replace them both... definitely need to get new ones, mine worked intermittently like you said and it was the old voice coil in the speaker shorting out.... new ones are flawless
Fresh Installed Memphis 6x9s.... roughly 100bux for the pair