Celowbe -
Without photos it's hard to tell what you're seeing, but I'll take a stab. First, I start at a thinning ratio of 3:1, paint to thinner, then make adjustments as needed following test spray. It's not very often that I thin 1:1, but sometimes I do if required.
I have never used Mr.Color metal lacquer, is it possible that like Alclad it's intended to be used undiluted?
Once I'm satisfied with my thinning ratio following test spray results, I set my pressure at whatever works best, usually 15-20psi, then holding the AB about 3-4 inches away from the model I spray an even, glossy coat, but no more than required to make the pass lay down smoothly. To continue passes past that point invites runs, (sags,) that resemble teardrops.
If the AB is held too far away, the paint particles dry before reaching the surface, that pebbly finish can only be fixed by sanding smooth, then repainting. I generally apply two or three coats, about 5-15 minutes apart, depending on the paint and air temp.
As to white spots appearing, the only things I can think of are partially dried residue in the AB being spattered on the surface, or possibly a reaction between paint and thinning agent.
I hope you get this sorted quickly, please let us know how you do.
Patrick