my 93 LS has a recurring problem while using halogen or xenon fusion bulbs. The socket you plug the bulb into will eventually disentigrate due to the upped wattage of the bulb. Perhaps yer socket(s) are hashed out, it caused my one bulb to shine yellow; or 'winking six syndrome' if you will, it occasionally came back on for the most part if I jiggled it or put the beams on. Look into the socket.