I had a similar problem, and while I was trying to sort it out one day a lineman with the power company stopped by and asked for access to a power pole on my property. He told me that there was a cracked insulator and as we talked he said that if I was using any LED bulbs one of the symptoms would be the lights flickering. It took him about twenty minutes to make the repair and I've had no problems since. Hope this helps, good luck.