The stereo keeps cutting in and out which isn't very noticable with radio stations. However when trying to use my add-on cd changer which does plug in not tune in on a radio station. It often is only in 1 channel and a humming hearing test noise is in the other side. Also when the rear defroster is on only 1 or 2 stations are even listenable. I had a 98 towncar with rear window antenna and no problem with the defroster. Any ideas on anything to check or fix these problems.