Jake,
Sorry to tell you this, but your vinyl parts are probably never going to dry. Solvent based paints don't agree with vinyl. I've done it, and even after stripping the part with Simple Green and using a plain water-based acrylic, the part is still tacky. And it's closing in on two years ago. The chemical reaction between the vinyl and the enamel paint just keeps going.
Same thing can happen when vinyl and unpainted styrene stay in contact for a while, they start to melt together.
In the future, try using only acrylics on your vinyl parts, and on any place where the vinyl will come into contact with plastic or other paint.
Paul