I have noticed that static in the radio on AM channels comes and goes for no reason I can see. I have other vehicles and the static comes and goes where the power lines are and as I live 25 miles from the nearest village I always take the only route available so I know where the static should be. On this STS it occurs where it should but at times it occurs in locations where it should not. It seems to be most prevalent when the car is not fully warmed up. Could it be the alternator or something like that?