Help! Paint splattering.

Please tell me where I'm going wrong, I have a gravity fed, double action airbrush which I have had for about a year now and I have learnt to use it to improve my painting. However, I have a big problem:

Now I know from good advice here that if my enamel paint is too thick, then this can cause a splattering effect, however I have found that every paint that I have put through my A/B today has splattered no matter how much I thin the paint. I have stripped down my A/B and given it a good clean, and it is still leaving small "bubbles" on every surface that I paint. I sprayed clear gloss enamel on a near perfect NMF model and now it looks ruined. I figured if I could fix my A/B then another clear coat on my model may save it from the sandpaper.

Any help on this one would be appreciated

Darren.