Congrats on your new acquisition.
First, go to your local ISUZU dealer and order the owners manual for your year and model. Second, go to your local auto parts super-store (PEP BOYS, Auto Zone, etc.) and buy the HAYNES REPAIR MANUAL for the ISUZU RODEO & AMIGO/HONDA PASSPORT 1989-2002,(All models). It's all the same book and will cost about $20 but is worth every penny.

It gives very detailed tune-up info and other tidbits. So even if you don't wanna do all the labor yourself (who does?), at least you'll know what's wrong when you take your baby to your favorite mechanic!
Good luck!
Lee