Sounds like you skipped the finishing work prior to the paint job. There's a lot of sanding, grouting, heat sealing etc. before you lay on that first coat of PlastiDip. Maybe check out the Evil Ted channel on YouTube, he goes over a lot of that stuff in good detail. Depending on what's left to do finishing wise, you might be better off stripping the paint and starting over, if that'll give a significantly better result. But that's up to you.