spray painting plastic

I dont think my long-explanation post went through, so in case it didnt, here's the deal. I am custom painting a Little Tikes car for my nephew, and cant seem to lay down a base-coat of gloss black without getting hundreds of little "pinholes" of imperfection with even the first coat of paint. Ive tried many many different prep methods, including filler-primer, and they just keep popping up. Ive tried different paints and various stages of sanding, and these little rackin frackin imperfections keep showing up before the paint has even dried to the touch. Help please!