big problem with my nissan 300zx na... would appreciate some advice

[RED300guru92]

Hello my name is sam and i own a red 1992 300zx NA. A few months ago a took it up to about 6000 to 6500 rpms and immediatley while driving i noticed something was wrong. My car has had a huge loss in power to the wheels, there is absolutely no pick up in it at all, when taken up to about 4000 rpms it just doesn't want to go much higher and the engine makes an abnormaly loud sound. Also, there is a really bad rattling coming from around the catalytic converter and sometimes i get some bad fumes. I have had it in the shop for almost 3 weeks now and my mechanic hasn't called me. So if any body could give me some advice on what could be wrong i would really appreciate it. thanks.

[aris_unlimited]

If you are getting a rattling noise from the catalytic convertor then it is quite possible you have a bad cat. If the "honeycomb" inside gets broken up it will rattle and clog up the exhaust. This would definitely reduce power, rpms, produce the rattle, and the fumes.