Unable to add a post

I’m trying to fix 404 errors on my blog. Some of the pages reference this page: wp1/thaiiland-new-mitsubishi-l200-triton-exporter.html but when I try to create this page, WordPress keeps adding “-2” to the slug as if the former page exists. I have searched the site but this page in fact does not exist and I’m getting a 404 error. Is there anything I can do to diagnose why I’m getting this -02 added.

The page I need help with: [log in to see the link]