Has anybody had a distinctively audible "growling" noise coming from the front of their Expedition? Mine is a stock '00 4x4 with a 5.4L. I originally thought the noise was a bad tire (noise sounds kinda like a truck with Monster Mudder tires coming down the road), but then realized that it only occurred during acceleration and is more pronounced between 0 and 30 mph, i.e. off a dead stop. As soon as I let off the gas, the noise is gone...hit the gas again and there's the noise. Whatever the cause, it has become extremely annoying.

 

I don't know about any growling noise but my stock '99 with the 5.4 started to make a whistling sounding between 2000-2400 rpms and only when in motion. It's driving me crazy.

- Dae