2000 Cadillac Deville Low beam headlamps

I have intermittent lowbeams in both manual mode and twilight mode. Parking, tail and instrument lights function properly. I have replaced the LB relay and have checked all the fuses. Someone already suggested the column dimmer switch, but I don't want to spend hundreds of dollars replacing that if it is a control module. When the lowbeams are working, I can switch back and forth from high to lowbeams without problems. That is why I question the dimmer switch. I also have a intermittent "service air bag" light which could be a faulty clockspring, or connected to the same cause. I even had a "service security system" light once.