As a long-time Isuzu owner (short-time with the VX) I've had numerous "noise" issues over the past years, which are very difficult to diagnose due to the way sound travels through the vehicle (sounds like its coming from the left-front, but the problem is really in the right-rear) and the multitude of variable causes.

Some of the things I'd check (in no specific order - just as they occurred to me):

Is the driveshaft straight, lubed and balanced?
Are the u-joints on the driveshaft lubed or binding?
Is the power steering fluid topped-off, low or too full?
Is the power steering belt tension sufficient?
Are any other belts loose?
Could it be the bearing in the power steering unit or alternator (hard to diagnose until it fails)?
Are any shocks leaking fluid? Any loose shock mounts?
Are any axle boots torn or axles leaking fluid?
What about the bearings in your rear axle?
Are any ball joint boots cut? How 'bout loose ball-joint mounts?
What is the condition of the rubber bushings on your upper A-arm? Any slop?
Have you lost any shims behind the upper A-arm?
Are your tires balanced? Could you have thrown a weight?
Are the wheel bearings seizing? Is there sufficient grease and is the axle nut at sufficient torque?

Lots and lots of moving parts - any of which could cause some noise issues.

Best of luck!