??Testors Flat Clear Acryl problem??

Generally, you don't need to thin Testors Acryl paints including their Flat and Gloss coats. They're airbrush ready out of the bottle. I don't know if this is the cause of the hazing though. You also might have sprayed too heavy of a coat. Testors Arcyl Flat is best sprayed in light coats.

-Jesse