I had the same thing only after I installed my kartboy. I reinstalled the OEM one to see if it was just the shifter and the OEM shifter also had the same problem now. I don't know if its something I did or just an odd circumstance. I had researched this problem very in depth and iirc it is a known issue which Toyota issued a TSB for. Of course you would have to reinstall your OEM shifter for them to do anything.
I don't know what the rubber underneath the sleeve thing is so I can't help you there. Maybe if you were more specific or showed a picture.
Only tips I can give is make sure you still have the small washer between the cotter pin and the shifter linkage. Make sure the shifter is properly torqued and not over torqued.
Mine sounded like this
[ame="https://www.youtube.com/watch?v=pZUr4rVIulA"]FT86 Shifter Rattle - YouTube[/ame]
In that video they reference this post which I never came across but funny enough I actually did the same thing.
http://www.ft86club.com/forums/showp...1&postcount=99
Final Edit: Found the link to the TSB in regards to shifter rattle.
http://www.ft86club.com/forums/attac...1&d=1367276498