I had the same stale, stinky smell in my 93 LS400 last year on vacation with the family. I checked the a/c condendation drain and found it was clogged. The rubber hose is detachable (be careful alot of water can be in there). After getting a towel to dry off my entire head, I was able to remove the dirt and reinstall the drain hose. Haven't had a problem since.