What you have is called orange peel. Pretty common with gloss paints. IIRC, it comes from too heavy an application. You have two options to get rid of it.
One is to strip the model down and start over.
The other is to buff it out. You may need to go to your LHS and and get a buffing set. These have sand paper bonded to foam pads with grits up to 32000. If you can't find that/don't have an LHS, try an auto parts store. They may have some of the same grits in sheets. Wet sand and bring down the unevenness. The finest grits will actualy bring back the gloss.