Ok on my 92 GT I have one fog light the works just fine, but one doesn't always work. once in a while it will work. So yea I know the bulb is good, would a bad switch cause this?
check the wiring around the fog light with the fog lights on... wiggle the wires around and see if it turns on... it sounds like that is the problem... the switch would make them both not work if it was bad
yep. it will be something from the harness next to the radiator forward, as BP stated above.
i dont know how the ground situation is on stockers, as mine were yanked the first day i got the car (cant remember). if there is a ground wire on the light, really check it. a bad ground can cause your problems. or just redo the ground. piece of cake.
i was having the same problem as you with mine with my stock foglights, one would only work once and a while so I took apart the fog light and noticed that the bulb wire that connects to the fog light housing metal was all rusted, so I sanded down the connection real good and sprayed it down with wd40, then put some dielectric grease and plugs it back in. Its worked like a champ every since. So to answer your question, its most likely the ground of the bulb itself inside your fog light lenses. Check it out.