Problems With Stereo

[unclechubbs]

:( soo on my lexus Gs 300 my nakamichi premium sound sytem has started to studder and at first i thought it was my ground wich i dont thnk it is cause i opened the hood and the ground is still well connected and now im thinking it is the stereo and i was wondering if i should replace it with an aftermarket one? but i need to know if the system has its own AMP? and how many watts, and ohm each speaker puts out? or if you guys may know wht the problem?

russ