98 Trooper preventative Maintenance

89,900 miles, 3.5L, never a problem except the occasional check engine light which is usually the result of not screwing the gas cap on tight enough. The only repairs I’ve ever done is to change the oil & air filter. I’m considering getting the timing belt changed as I plan to keep it as long as I can.

What’s the Isuzu’s history on timing belts? Am I messing with a good thing by doing this maintenance? If I do replace the belt should I also replace the water pump? What else should I do?

Thanks in advance!