Toyota Repair: VSC and Check engine lights, vacuum hoses, oxygen sensor

Question
My 2002 Highlander V6 4WD is giving a "P0420" code for catalytic converter not meeting performance standards according to the output from my converter output oxygen sensor.  Is it possible that anything other than a poor performing converter to cause this code ?  Also another post I saw mentioned vacuum hoses off would be a good thing to check. I checked and found 3 hoses near air filter, 2 connected and one stub with a plug in it ? ? ?  Is that by design ?

Look forward to hearing your professional opinion,
And definitely don't look forward to a $1200 converter job.

Thanks Ted.       Pete

Answer
The P0420 code is pretty much specific to a cat converter problem,i can also be caused by other engine problems like a lean run condition but you are not getting any other codes. Have you looked around the air filter area for any hoses that may be off that should be on that connector you mentioned, did you recently buy it or have you owned it longer?