The AMM is a giant black cylinder that is basically located on top of the air box in the front left corner of the engine compartment (front left being the corner closest to the passengers side headlight). A hose comes out of the airbox, connectes to the AMM, and anlther hose runs back to the turbo. Their is an electronic connector that clips into the AMM on the top.

The picture at the bottom of this post is a new Bosch AMM. They are VERY expensive new, so you should see if you can find a good used one for cheap. A new Bosch one costs $266 online, while a non-branded new one can be had for $166. Both prices are from the parts site I use, http://www.importeccatalog.com. At least the 2-day shipping is free on orders over $50.

If you can't find a used one dirt cheap or a used one you KNOW (with certainty) to be good reasonably cheap you should suck it up and go new. At least you'll know it will last a while and won't cut out on you inside a month.

good luck,
rt