It could be your paint. When paint gets old the pigment particles can begin to stick together and make little clumps (flocculate). And, the tiny .2mm nozzle makes this especially a problem. If the airbrush sprays thinner OK, it's probably not the airbrush. Also, your compressor is probably marginal for pressure and volume. That doesn't help either.
You might want to buy some fresh paint and see how that works.
Don