What I found with my 97 was the seal around the foglight casing did not have a great seal. If you look around at night you will find that many 2nd gen explorers will have at least one fog light out. What I did was remove left and right housing. It was very simple just loosen a nut and it is on a pivot, it just swings right out. Then I cleaned it really well to make sure there was no debris in it. make sure you do not get the inside very wet if so let it sit for a bit. Then I took clear silicon caulking/sealant and put a thin bead around the houseing(the clear housing is actuallt two pieces). It is where the front clear plastic connects with the back piece. This is where the humidity and water was getting in, even though I never saw it, it only takes a bit to burn those hot bulbs, and the fog light location is perfect for wet pudles. After I let the sealent dry I reassembled. I was going through fog bulbs once evey 3-6 months, after the fix I went two years without them going out, they may still be working but I will never know I traded it in for my 04! Good luck!