This is the weirdest thing I've ever heard and I can't find the source. A few weeks ago, my 2001 Bullitt made a noise so loud and so deep I honestly thought it was a fog horn. It lasted a few seconds while I was sitting in the parking lot at the gas station it idle. I don't remember if I had my foot on the clutch or not, but I think I did. Since then it's done it maybe 10 times and a couple times it actually killed the motor or slowed it until I blipped the throttle. It always starts right up and if I let the clutch out and drive, it goes away very soon. I pulled the serpentine belt and spun all the accessories as well as listened to it at idle for a few minutes. Everything is dead quiet and there's no wear on the belt. My other concern is that it may be the throwout bearing, but I've had it happen with the clutch out in neutral as well. Any ideas? Anyone had this happen. The car just turned over to 110K and has led an easy life. It's also my daily driver so I need it to be reliable.