Those black specks can be ugly to look at, and very frustrating to get rid of. Paint Shop Pro is notorious for adding distortions that will result in these blemishes.

So, for example, let's look at a fragment of our picture. It looks fine as it is.

Use the fill tool and set the tolerance very low.

Now fill the transparent area of the texture with a radically different color...one that will not bleed into the other parts of the image. Now, we see all kinds of problems.

All those spots that were not covered by the fill will show up in the game. They will not be transparent. The trouble is that the RGB values are not 0,0,0. Anyway, paint over them using the same color that you filled with. You should end up with something like this.

Once done, back fill the transparent area with black once again. Set the tolerance somewhat higher.

The specks should be gone.

Save the texture and try it in the game. You should see improvements.