Psi depends a little on the gun setup you have. I spray clear at about 35 psi with a sata rp 1.3. Not all clears are the same, but most like a little higher pressure to break up the droplets. The spec sheets on the clear should tell you the best gun setup. Some of the small specs look like they could be solvent pop, but usually when you have them, there's a lot more of them. The big specks are probably dirt nibs. Solvent pop is usually caused by too little flash time between coats, or over application per coat. If it is pop, sanding and re clearing probably is your best bet since those little bubbles would probably be all the way through the clear film.