IMac stops responding when I use FCPX 3D text

Well, first off, you have a 2009 iMac which has very outdated hardware considering that the pic is almost 7 years old. The 9400 you have does not have enough power to run 3D applications. I'm surprised you haven't seen the sluggish performance of your iMac.

FCPX 10.2.2 has a 3D text engine. You don't really need a plugin. But, as Kermis has accurately pointed out, your system is really not up to the task.

Just a few notes for the future: 1) these plugins usually offer a demo version, which you could test to see how well it works, or not;

2) 3D stuff usually requires a pretty up to date GPU in order to perform

3) Did you know that FCP X has quite great 3D titles itself? Did you try and see how these perform? (my guess: not very well)

I also have a 2011 iMac - the moment I installed FCP X on it it warned that 3D titles would not work to the fullest on this machine.