I have a 1999 4.0 and suddenly, the radio will not go off or allow a station or volume change. Then, out of nowhere, it will work fine for a few moments, and then go back to no effect with the controls. If it were a fuse, it would not work at all, but it is intermittent. Was able to put in a tape, and then could not get it out or change volume, and then it worked again. Help...