For the past 3 weeks, my headlights have been flickering at night ( usually within the first 5-10 minutes of driving,especially over bumps). A few times they shut off completely, only to come back to normal within a few seconds. I took it to the dealership and they couldn't find anything wrong, so they just changed the bulbs. I brought it back and they did an electrical diagnostic, and found that there was something wrong with the headlight assembly switch so I had it replaced. The problem continued so I brought it back again. This time they said that it was a daylight running light relay issue. So I had that replaced. I'm STILL having the problem. So apparently they haven't a clue what is going on and I'm tired of paying for parts that I apparently don't need. Any ideas for what could be causing this?