After 15 Mins. of driving the headlights start to flash on and off. I tried replacing the light switch with no luck. Two different mechanics have no idea whats wrong! There's got to be someone out there who knows how to fix this. It's a Ford Ranger Splash, 4.0L 6cyl. extended cab short bed 4x4. I did have a lighted moonvisor installed, but had no problems until several years after installation.

Sounds like the multi function switch might have a short.
I have a explorer that bacisly had no headlights but only brights.
The multi function switch was the problem.
you could also check the fuse located in the box in the engine compartment.
It will be a 40 amp red fuse.

have it serviced