I may be wrong in chimming on this issue, but are you using the Kustom Kolor enamels?
If so KK has a reducer for them.
It sounds like your reducer is not compatable......or as stated you need a straining system......
cut a piece of panty hose and ad between the cap and bottle of the paint.....
or Don has posted this in tutorals
http://www.howtoairbrush.com/paint_strainer.htm