Sounds like you are using the wrong throwout collar, don't believe it's the slave.
What size clutch/ pressure plate do you have (225mm or 240mm?) and which collar are you using (L28 NA, T5 or Z32 NA?)? If you have the 225mm clutch kit, use the longer NA collar, if you have the 240mm clutch/ kit, then use the shorter collar from the T5 trans, if you don't have the shorter T5 collar, I believe the collar from the Z32 NA should work just fine ( it was almost identical when I did a comparison with the T5 collar).