How do I know if my catalytic converter is clogged?

I have a 2001 Nissan Sentra GXE and I believe the catalytic converter is clogged. It runs erratically, loses power suddenly on acceleration, and seems to have all of the symptoms of a clogged converter however when I rev the engine while in neutral it does so normally.|||You need a low pressure gauge pluged into the pre cat o2 sensor hole,and when running it shouldn't read more the 2-3 psi,getting up to 8-10psi and the exhaust is chocked/clogged.


Or,if you dont mind noise take out the pre cat sensor and drive it round the block,it'll sound like hell but if it goes better it's a pretty good bet the cats clogged,|||pull the o2 sensor out and see if that changes the way that it runs. it does not sound like a plugged cat to me.