The 1997 to 2001 QX4's were notoriously underpowered for a luxury SUV. The V6 engine produced a paltry 168 horsepower. An upgrade for 2001 included a more powerful engine making 240 horsepower.
The later models had a problem with the coil ignition system. The early models did not have this problem because they used a ignition distributor.
The only transmission made available for this SUV was a 4 speed automatic.
Although it had many faults, the QX4 is known for its off-road ability. The low range four wheel drive and over 8 inches of ground clearance make it a natural vehicle for offroad excursions.
These are out there on the used car market, but you'll probably have to look hard for them. You might find one in your local classifieds, but Craigslist and eBay are probably better options.