intermittently flickering headlights on 1990 Ford Mustang GT

my headlights will go off for no apparent reason and come back on when they get good and ready. Seems to be no pattern. Is thia a headlight switch, fuse, circuit breaker, high beam switch, fog light switchproblem or what. It doesn't seem to matter if the fog lights are on or off. Kinda scary at 70 on the interstate.

Asked by for the 1990 Ford Mustang GT
Unplug the headlight swich and look closely at the connector that it plugs into. I have seen some of these melt from high resistance in the circuit. Do you have aftermarket high amperage headlight bulbs? We sometime see this overload the circuits.
yes i did change the headlights to a one piece set and i added the new wire that came with the sets.
2 more answers
headlight switch is bad
intermittently flickering headlights after about20 minutes no matter what i do at 40 coming the city.please help me if you can.