just installed a oem clutch and release bearing in my 05z but i am experiencing a problem. before 1500 rpm and after 4000rpm it feels like there is a vibration. the flywheel was a little scored so i took it to have it resurfaced,a guy that works with me(by the way im a ford mechanic) says the flywheel probably became unbalanced when they machined it. the vibration isnt real real bad any suggestions would be very appreciated and thanks in advance also before i started working on the z i started to notice when downshifting the same vibration was present but only when downshifting and my wheel bearing on the right side has been needed replacing.

 

Stock flywheel? If it was resurfaced more than likely it wasn't done correctly. You are not supposed the resurface the stock dual mass, it would be very hard to get it to cut straight and would cause a vibration if it was not cut perfectly flat.
The clutch surface of the flywheel floats on the main body and will not sit flat when you cut it.

I would not let it go, harmonic vibrations can do a lot of damage to an engine.