Ditto on the cleaning of ALL contacts. Most of the problems are up by the fog lights and the ground connection. Inside the fender is a ground block check and clean the connection. The wiring could be going bad due to age and environmental concerns. First check that you have power going to the light by using a Volt meter and using a different ground point. If you have power showing then it's a ground problem. Use the connector that is not connected to the bulb. A lot of the time it is the what they call a pigs tail that is bad. It is a short connecting wire(Under 8"). Just try to get one side working first then the other. Oh by the way You did put in new bulbs in the new lights?