I haven't crawled underneath yet but thought maybe somebody has had a similar problem. It sounds like it's in the area of the transmission mount. If you grab the intake plenum and shake the engine you can hear it a little bit but when you hit a bump it comes through loud and clear. The car is a 93 Intrepid with a 3.3. Some of you guys might remember me asking about a sooty smoking problem a while back. It turned out that it was the O2 sensors.