@kevinmason could be an issue with the throttle position sensor. Check for a cracked or leaking air intake. If you start your car, let it idle and spray some WD40 (or starter fluid) sensible around the intake, you will find a leak. Once the engine idles even higher when it gets those vapors, you know you have a leak. Of course, you can't rule out a computer malfunction etc. I suggest you get your Ford scanned and see if the OBD pops some codes.