How do you tell if you have a bad Catalytic converter?

[Lippy]

'88 GW completely bone stock. My temperature stays up around 220 and I can't go by a gas station. No power on hills. Anyone run across this problem? I've been told it is a bad catalytic converter. Any input would be great.

Lippy
'88 GW stock 70K

[GasWag]

Ive heard there is a sulfer smell and would cause lack of power. try hitting the cat a few times with a rubber hammer and see if you hear some rattling around. Usually the cat never goes bad(ya right) they say if it goes bad there could be something else causing it to go out. I would take it to one of those places that does free exhause inspection and they can tell you if it is bad or not.

[AMC258]

disconnect it at the donut gasket, and take it for a short romp, if it still does it, then that wasn't it, but it sounds like you were told right.