I have a 94gt with the Mach 460. Ive had this problem that I cant seem to figure out. The radio stations like to fade in and out. Some stations that are 15 miles away barely come in. If the car is turned off I can get everything perfectly. If the car is running.. forget it. I have switched out the factory unit for a Sony and I still have the problems. I have even gone to add an antenna booster and noise filter. Nothing has helped. I dont know what else to change except the wire and actual antenna.