Rattle
I have just had the same exact problem with my 2005 GT convertible with 45k. It turned out to be an "inspection plate" under the car that covers the bottom of the flywheel. Apparently this is what is removed to inspect the flywheel for wear and soforth. Anyhow, it turns out that the plate was bent and rubbing against the flywheel. Your symptoms were the same as mine but mine went away once the car was warm. Hope this helps. Now the battery went bad and it won't start. That's ok since the weather is bad and the car does not get driven in any inclement weather.
I have just had the same exact problem with my 2005 GT convertible with 45k. It turned out to be an "inspection plate" under the car that covers the bottom of the flywheel. Apparently this is what is removed to inspect the flywheel for wear and soforth. Anyhow, it turns out that the plate was bent and rubbing against the flywheel. Your symptoms were the same as mine but mine went away once the car was warm. Hope this helps. Now the battery went bad and it won't start. That's ok since the weather is bad and the car does not get driven in any inclement weather.