Your Amps are going, and sounds as though you may have a ground inline some where. Bose are not, known for reliability, and are consequently rather gimmicky....it will cost you an arm and a leg to repair, so my advice would be to gutt it out, and put in a custom stereo system...It will sound and look alot better! Make sure to go with external amplifiers, good mid/high door speakers and a nice head unit accompanied by a subwoofer and the difference will be night and day....At any rate the Bose are a lost cause, and if you are driving a 1990 consider yourself lucky they lasted this long! My 1994's died over a year ago! Just my thought and opinions.