honestly from the OP it sounds like an airflow issue. make sure the coil is up where the air will hit it a little low.. make sure there is some breathing room underneath the coil and make sure the airflow is lined up with the coil directly.
A hot spot will still give you vapor, it will just be super harsh..
not enough
juice isn't likely, it would be hard to miss that you don't have enough
juice.
Your juice may be a bit high as far as nic goes, but that would present itself more in being over nic'd. You would get a harsh throat hit, but it wouldn't effect the vapor production at all.
+ make sure you have the post screws tightened down well. Not far enough to cut through the wire, but snug enough that it's making good contact and won't back out.