Are you using voronoi for your stars? PFs have varaition noises and stuffs and I don't know if you can actually fully disable such a effect on them (hence the issues with warping roads and stuff due to the 3D nature of the noise and all the variation of it).
Also remember you need to use Smooth AA, which doesn't have edge reconstruction. Otherwise, shapes will sparkles/flicker, etc. Kinda like you'd doo for compositing and stuff you wouldn't use AA with effects, and instead apply any of those effects like hard edges in post on the whole composited scene.