Radio static
Ok, this is weird, but true. My wife drives a 95 Limited, we've had it for 11 years, since it had 33k miles. Almost immediately we had seriously obnoxious static every time I drove the car but never when she did. We're kinda slow, but finally figured out it has something to do with the position of the power seat. Easy fix, I just don't drive her car.
So maybe yours has some other short, far away from the radio. Move your seat around and see what happens.
Good Luck.