This problem came up 3 months ago. Yesterday I came across the same problem when I researched Complaint Problems with 2009 Ford Focus. This morning I took it to my dealer. I explained to the Service Manager that I had found a similar problem. He was aware of something of rhis problem. He asked if I turned off the A/C or the defroster when I shut the engine down. I said always. It appears that when these were left on they would collect some condensation on some part that caused the vibration. In my case it would happen one minute, and another no problem at all.

It hasn't been fixed. They don't feel it. My salesman drove it and said he felt the vibration but the shop foreman says he doesn't feel it. Called customer service, she said there's nothing she can do about it. I've been back 3 times. When I first got the car, brand new, drove to daughter's 600 miles roundtrip. No problem. OK ride. Now I get a buzzing feeling in my foot when accelerate at any speed. It is there on all different road surfaces. It is very annoying and is driving me nuts!!! It started around 3,500 and I now have 4,200 miles.

Update from Feb 23, 2010: I now have 6700 miles and the buzzing sensation is still in the gas, brake floorboard. It is continuous. After bringing the car several times, (they don't write it up,) they say it is the same in all the focus's. So it appears that I am stuck with it.