My 2000 LS V8 with approximately 42000 mi has a radio noise problem. In addition to the station I've tuned in or CD I'm playing the speakers are transmitting the sound of the spark plugs firing. When you rev up the engine you can actually hear it through the speaker system. (When the engine is off radio plays beautifully.) I evidently have a radio frequency (RF) shielding problem. Has anyone else experienced this and do you know what was repaired/replaced to cure the problem? Was it near the antenna or near the radio?