Ok, I have gotten the car to do it again. This time, I left it in "On" for about 5 minutes while I was cleaning out the interior. It would not buzz in ACC, but with it in "On" but motor off, the buzz was definitely back. I still cannot track the sound, but it looked like it was coming from under the Duratec dust cover over the IMRC. It was definitely coming from between the battery and the motor. Could it be fuel system related?
