I had the same problem. The only thing that got me out of it was to force myself to write a lot of Perl code (not so bad) that used map, grep, and foreach style (very awkward at first). The new approach became more natural after a few weeks. I completely forgot about my older style after a couple of months.

Really, the best way to stop writing C-style Perl code is to start writing Perl-style Perl code.