Help with whine noise

Ok for the past month or so the Rodeo (98 3.2L) has been making a sound that I at first thought was the power steering (we all know that sound). Well I checked the resevoir at it's still in the max range. I followed inspection tips to see if the fluid level would change. What I noticed is the noise was not present when turning in either direction. I also noticed that the noise is only audible when I stepped on the gas.

So then I crawled underneath thinking maybe the trans is low. I found a small leak so I figured well maybe I am just low from the leak and the leak was caused from a corroded gasket. I drained fluid and changed the filter and gasket. On a side note, I was able to get the pan off without taking the trans cross member off as well. I just used a 1/4" drive 10mm socket with a universal joint and a 4" extension. Anyways, the common Dexron bath took place as I was pumping the new fluid in. Once I got all the bolts torqued I drove it around to see if this cured my initial problem. NOPE!!! Nothing is ever easy with these rigs.

So now I am clueless on what the next possible part that could be causing this noise. If I had to describe it I would say it sounded like an electric cart (much like the handicap carts you see at wally mart). The more gas you give it the louded and high pitched the sound is. From what I can tell the noise is coming from the back of the engine, but I could be wrong since it is possible for the sound from part can be echoed throughout the engine bay. It makes the sound no matter if you are driving or parked.

Vehicle info:
98 Rodeo S 3.2L
108,600 miles
Trans rebuilt at 60K
Major items on to do list = timing belt,idler pulley,water pump, and thermostat.

Wow this is my first long winded post. Thanks for any help.

http://www.geocities.com/endre_rl/isuzufaq.htm#faq5

I also would say to check for leak in exhaust system.