Can't find the last monkey idol. Where is the monkey that drops one?

Can someone please help me out? I have found the 3 monkey idols from the three chests but I cannot find a fourth. I see people on the message board saying that it can be found on a really fast monkey but I have killed everything in the place and none of the monkies I have killed have dropped idols. Anyone out there know where this one roams?

thx
warblade

I saw him once near the hidden door to the statue of Kerah, but I did not kill him at that time. When I caught up with him again, he was stuck at one of the doors in the storage room (the one with a row of 6 doors where you have to pull the right combination of levers to open them). You'll know him if you see him, because he not only drops the statue, but you can see it in his hands, and its fairly big compared to his body.

[Wyvern]

There is a room with a chute in the middle which is described as being too small for your characters to use. In that room is a lever. Pulling the lever releases monkeys which were you not there to clean up this unholy place would be shoved down that small chute to feed the unspeakably evil naga. One of the monkeys released by pulling that lever carries the 4th monkey idol.
Wyv