ballasts. i could almost bet my car on it lol. iv had 5 sets of HID's and had massive problems with the ballasts in my grand am. they would flicker and sputter and if i turned my brights on, when i went back to low beams they went off completely. its a 99 GT so it has 9007's in it so it only made sense that the ballasts went bad. i borrowed my buddys old set (which happened to have been a thicker larger ballast) and switched it all out and they worked like a charm and were even brighter than before! after inspecting the ballasts i found that one had been burning you could smell the burning electrical in it. and that caused everything else to go haywire. best way to tell is if you still have your stock bulbs, remove the HID's and put the stock bulbs in and check and see. if the stockers are the same then i would bet its the ballast. if you got a cheapo set off ebay then the odds of it being the ballast just shot up lol..
