corolla 2001, with P0420 code

[kulkarni_ash]

Hi
I had post one message before here is the link for it
http://www.toyotanation.com/forum/t186775.html

I did some more work with a mechanic who wants to change catalyst on it, which i dont want until some more test and ideas.

I get error code P0420 Catalyst System Efficiency Below Threshold (Bank 1).

I did the following
1. I had the code reset and drove for about 60 miles that day, the light did not come on
2. I checked it on machine same day, it showed catalyst and EVAP not ready, 02 sensor ready
3. Next day i drove for 10 miles the light came back on.
4, Checked it catalyst is ready but EVAP is not ready but 02 sensor is ready

Any ideas or suggestions, i had the original 02 Sensor (which i changed last year, same mechanic) and was willing to put it on and try it again which he says he wont do.

Ashish