I installed the ignitor and it worked as it should but found that wasn't the problem. It turned out to be the pilot burner and a contractor friend of mine had a new one which we put in and the furnace now stays on like it should. I figure
that on a 31 year old furnace, that sooner or later the old ignitor will fail, so I left the new one in and kept the old one for an emergency. Very happy with the price.