oh, i did want to add, that while i dont know if wifi would interfere with a AM radio signal...it is possible.
i mentioned that near my house(about a 10foot square area next to the house on the driveway) all of my AM and FM radios glitch, and i have to get closer to the car to re-gain control. i dont have wifi, or anything else that i know of that should cause this. its just a "dead zone"...lol
my 2.4ghz radios arent effected tho.
i hope you can get the issue sorted in time. good luck.