Odds are it is just the wrong part. If for some reason it's not and your slave cylinder is pushing the fork and holding it, it's probably your clutch. I had the same problem, I even replaced my slave cylinder with a new one from mitsu, but it ended up being a combination of the clutch and probably the pivot ball. I pulled the tranny this past weekend and noticed that the ball had a chip missing out of the top of it to where the metal shaft in the middle was showing. Also the clutch fingers had been worn down so much from where the throwout bearing rides against them that they were almost paper thin. It had 150k on it.

-Roman