The flywheel should have been resurfaced. They glaze from use and could cause the problem you described. As far as the pressure plate, normally, it is replaced with the clutch. However, I have known of mechanics that will only replace the clutch disc. As a result, the pressure plate is weak from age and can cause a chatter.
You may want to ask him / her these questions and explain what is happening. Perhaps they will take a look at it (for free).
Let me know if you have other questions.
Joe
Saturday, January 1st, 2011 AT 10:41 PM