Here is an easy way to fix the airy draw on some cartomizers.
Take a carto condom like this...
and cut a section off like such...
then make a partial cut along one edge like this..
.
Then slip this over your cartomizer and slide it down so it covers one of the draw holes like this.
You can also cover two holes or one and a half or whatever you like. A simple fix that works well.
cheers,
Neil