I have a 99 Cadillac Escalade with 96K mi and have ignition noise coming through the radio. This started about 10K mi ago and thought it was corrected when it was found that the distributer cap had a crack. The noise went away after replacing the cap, rotor and wires. The mechanic verified the ignition with a kilovolt meter and indicated all was well. 10K mi later and after the engine warms up, the ignition noise is back. Thinking it was the cap again, I replaced the cap and rotor and spark plugs (just for fun), but luck. Any thoughts?
There may be a bad plug wire causing the trouble. A bad antenna ground will cause that problem also.