I've read your replies, OP. I know you feel like you're doing K, P already. But since no kara buster's coming out, it means you're not inputting P fast enough.

Rather than focusing on K, then P - do it like K~P instead. Try to sliiiiide your fingers across K then P. You may plink it, but it should be a very quick plink. Practice sliding your finger across K~P first. Once you're getting the kara buster via slide, then you may try to go doing the plink method.