P0455 in a '98 New Beetle.

I keep getting a P0455 code, EVAP leak detected (gross leak). I've checked all the lines for a break back to the charcol cannister in the right rear but everything is intact. Could it be the cannister itself?
Any ideas would be appreciated. I'm starting to detect the smell of an unhappy catalytic converter. The smell of unburned fuel is apparent as when you have a vacuum leak. Also, I'm experiencing an intermittent lack of power when I accelorate in 1st and 2nd. Thanks.