I think I have cracked this now. It seems I when I was leaving it stood up it made the throat hit really bad, no matter what the level of liquid was. But having it in laying down or in a horizontal position really reduces the throat hit, I am having to increase the voltage on the ego twist to increase the throat hit. So it must just be when it is stood up/vertical the amount of liquid reaching the coil is not enough and makes it burn a lot more. Would this make sense to you guys?
This got me thinking and I think I am now going to purchase a bottom coil EVOD or a Protank 3 knowing the liquid I have is fine.