Paint spitting isn't normal and there is definitely a problem. What paint/thinners are you using and ratios? Normally when the paints spits, it's too thick and collects at the tip of the gun and when enough paint has accumulated at the tip, the air brush will spit it onto the model. If the paint is spitting 100% of the time; the paint isn't mixed well or bad paint or the air brush is the problem.
My normal shooting at 12-15 "working pressure"
Tamiya paint: Thinned with Tamiya Yellow Cap thinner: 60 parts thinner to 40 parts paint.
Model master Enamels: 40% MM Thinner to 60% paint and sometimes 30/70.
Iwata HP-CS Eclipse
I also shoot very close to the model - no more the 1-2 inches from the surface
How bad is the humidity when you paint?
I'm starting to think it's your air brush. Do some testing with you Neo and see what happens.