Need paint advice - first time using a primer under the topcoat.

Long-time lurker and now just joined.  I would say I am in intermediate modeler and I build mostly cars.  I am currently working on a 1:12 scale Doyusha Lamborghini Countach.  

For most of my years of modeling, I have been using rattle cans and no primer.  I know, I know... Not the best technique, but I usually get pretty decent results anyway.  I prefer Tamiya paints generally speaking.  

This time, I thought I would use a primer to see if I get better results.  I used Krylon Colormaster black (the Countach will be black).  I ended up spraying three somewhat light coats with sanding in between and after (1,000 grit and then 1,500 grit).  I just finished spraying color coat (Tamiya TS-14 acrylic lacquer black).  I sprayed three coats (15 minutes between coats).  From a few feet away the finish looks awesome.  But up close you can still see a little bit of "grain" from the primer.  This is after about an hour of drying time.  

My question is:  What next?  Will a couple of coats of clear smooth this out?  Do I need to color sand with 1,500 grit?  I'm afraid to sand down below the topcoat.  Do I spray the clear and then polish from there?  Or am I screwed and need to start over?

Any advice would be greatly appreciated.