honda prelude VTEC big loss of performance.

Hi everyone,
I have a 1993 Honda Prelude VTEC. I recently started having this
problem where the engine pulls fairly well all the way up to, oh about
2200 rpm, and then it almost feels like a brake is being applied in the
engine, the needle moves sluggishly and doesn't want to respond quickly
to gas inputs. This lasts to about 3000-3500rpm and then it feels as if
the engine lets loose again and the needle goes fine all the way to
redline. In all these other rpms the engine feels fairly poised and
smooth. However at 2.2 -3.5 k its just sluggish and sometimes the car
even jerks a little under constant throttle and in gear. There is also
a subdued grinding sound seemingly coming from under the car right
under the gas pedal and an ugly note in the exhaust. This doesnt always
happen but has been hapening more and more recently. My clutch was just
recently replaced. I also noticed it does not do this when the engine
is cold, say in the morning after leaving it over night. However once
it gets up to operating temperature it starts doing it. One of my
friends has suggested it might be the catalytic converter, as during a
recent smog test i barely passed in the HC(hydrocarbon) category. Any
insight, please?

 

The fact that this occurs after warmup (along with the sluggish, stuttering
performance) suggests the oxygen sensor may be near or is at complete
failure.

Most inexpensive source of OEM oxygen sensors I've found:
https://www.automedicsupply.com/

The grinding sound, though, suggests other possibilities as well.

www.autozone.com has a free online manual for your Prelude, for your
reference.

 

I've gotten the grinding and buzzing noises on slow O2 sensors. It's
unburnt air and fuel going through the catalytic converter. I'm sure
it's very bad for honeycomb cats.