Definitely the headlight switch. Built-in circuit breaker is failing; same symptoms I had. Easy replacement (unless you have really big hands). Got mine at Mustangs Unlimited, like $25. Took me 10 minutes...easiest fix I had to do and I had been putting it off. Push on release button on the switch body behind the dash(right side)with one hand and pull out the push-pull switch lever with the other. Pull off the wire coupling on the left side of the switch body. Put a screwdriver blade in the slot on the bezel and turn it while holding the switch body. Unscrew, remove old switch. Install new switch, plug in wires, put bezel back on, insert push-pull switch until it clicks. Done. Bezels are readily available if you wreck it.