I've got a IIci in which a capacitor on a cache card actually blew while in use two years ago. The IIci still reeks inside (but not outside or when it gets used).

Baking soda has been mentioned a few times. Try getting a few boxes of the refrigerator baking soda. It's the same size and price as the regular box but has a filter on the front. It worked wonders in my fridge, which had an odious stench coming from it. I had no idea what was causing it until I found a very old cucumber rotting in the back...