1995 Mercury Mystique mileage: 162,000. The problem the car is having is in the air filter area. A mid-pitch noise comes from the air filter area (sounds almost identical to the sound a conch shell makes when blown). My mechanic looked at it and showed me where the noise was coming from. It only happens when you either have been driving the car and come to a stop or when you rev the engine. As he demonstrated for me by having me rev the engine, he could feel the air filter box vibrating. As soon as he unclipped the box and lifted it up, the noise went away. However, I completely removed the air filter and box and then tried to rev the engine. The noise was still there, but it took a higher rev to produce it. I was wondering what I can do to keep this annoying noise from occurring again.