The 2.6 has timing chains, so no need to replace that if it isn't making an unholy racket (esp. at startup), but adjusting the chain guide may be advised (not sure if '89s have a manual guide adjustment or hydraulic auto-adjust?).

The maintenance light is primarily just for checking/cleaning emissions stuff. Once you remove the dummy switch cover as royster explained, the toggle-slider switch to reset the light won't be immediately obvious; you'll need to peer in there to see it, attached to the bottom-right corner of the instrument cluster, may need to reach in there with a screwdriver to flip the switch.