accelerator buzzing/vibrating

Thanks for the replies. Took it to dealer service for a check. Day before was buzzing like crazy, like I said around 2100-2200 RPM. Could not duplicate at dealer. I have bought 4 cars from this dealership in the last 5 years. They are one of the good ones, always go out of their way to address my concerns. They looked the car over and did find a bolt loose on a heat shield under the car. Like I said couldn't get it buzz that day. A week goes by all is well and then it's back, but only for a day. Hasn't done it since. It appears that it is also outside temp related. The day before I took it to dealer was a warmer day ~46 F. The day I went to dealer was ~36. It stayed cold after that for a week and the next day that it warmed back up is the day it started again. It has been cold since and no buzz. Go Figure. Talked with the tech at Ford and we decided that there is nothing to do but wait till it warms up again in the spring and see what happens. One reply talked about a loose heat shield and I think that it's something like that. There is another heat shield up higher than the one the tech tightened that seems sorta floppy to me. I may try my hand at tightening that one if the weather warms up for a day and the pedal buzzing returns. Again thanks for the replies.

Wanted to revisit this post to update as well as get it up front again, as I still don't have a solution. The dealer I work with has an excellent service dept. and they are really giving an A+ effort to try and resolve this. Still I value feedback from other Fusion owners who may have had similar issues. So far all TSB procedures for noises and or vibrations have been performed by the Dealership under warranty and without me pressing the issue. As I stated before I am lucky to have found one of the good dealerships. All heat shields have been checked, isolated removed and reinstalled. All cables and lines have been checked, insulated and rechecked. Nothing seems to be grounding to anything near or connected to the accelerator pedal mount. I probably have the quietest Fusion cabin in existence, no rattles no squeaks nothing, you can barely tell the car is running sitting at idle. Yet I still have a buzzing/vibrating gas pedal at around 2100 RPM. Only when warm and crazy as it sounds only when the weather is fairly warm. First had this checked in Nov. 06 at which time it disappeared. Reappeared only a few weeks ago when the weather here broke back into the 40's. Any ideas would be appreciated by me and by The service techs at my dealership.