Furnace sometimes fails to ignite, despite extensive replacement of parts
I have found there is nothing more important than a good ground on units doing this and I mean "A GOOD GROUND". Run a second one if necessary to your burner manifold and ground it to the frame somewhere that will give you a positive ground.

Then do the same with your control board. Make sure the transformer is feeding the control system correctly too. Not trying to doubt you, but sometimes people wire the output and common wrong. I have seen it. If the igniter is still erratic, sometimes the diaphragm in the draft switch doesn't make the switch because of trash floating around in the thing and the nipple getting partially plugged. These are just things I have found on jobs.