2000 Miata - Check Engine Light

Looking for advice on a recent problem ---

I have a 2000 Miate which started running horrible all of a sudden --
check engine light on steady and then flashing and then on steady
again. Spoke to my mechanic's assistance and was told to drive it to
his place but watch for oil pressure guage and water temp guage and
not to "push" it.

Started driving it (even though I really didn't want to). Drove maybe
10 km and then I was sure I smelled something "burning" so I pulled
over and had it towed.

Turned out to be my ignition coil. Had it replaced. The next day my
check engine light came on again. Took it back, he checked it out and
checked the settings for the Catalytic Converter (which showed OK).
Figured it was maybe just running through stuff that had been in the
gas tank when I had the original problem), and cleared the codes.

To make a long story short, I have had the check engine light cleared
a couple of times now but it has come back on. The code says
something about the O2 sensor (or something like that). He is now
saying that I need to replace the Catalytic Converter (its around
$1200) !!

Is there some way I can be sure that it's the Catalytic Converter?
Can it be tested someway BEFORE I spend that kind of money? Could it
be just a sensor of some sort or a loose wire?

I live in Ontario where we have E-tests -- could having an E-test
check it out? (I JUST had an e-test in mid October and everything was
fine).

Not sure what to do but it's getting colder and I need to put the car
away for the winter but want to get the problem solved before I do.

Does anybody have any thoughts or suggestions?

MUCH appreciated.


Carol