Evap leak - P0456

I've got a P0456 code on my 02 LS v6. I came to a stop at a light, RPMs quickly dipped twice from 800 to 400(ish) then went right back to normal idle (800-1000) and the CEL lit up. It seems to be running fine other than the RPM drops after coming to a stop.

I checked the gas cap, everything seems OK there. Checked the hoses coming into/out of Evap valve (well, assuming this diagram actually points me to the evap valve: http://ww2.justanswer.com/uploads/hdgene/2009-09-21_015429_ls_evap1.gif) and there were no major/detectable cracks. Any other hoses/fittings you guys can point me to that I should check?

I'm open to ideas.

Thanks.

How old is the battery? I experienced a stalling issue with my wife's V6 LS when coming to a stop and the issue ended up being due to an old, slightly weak battery. The battery was only 3 years old at the time. I don't recall having any diagnostic codes at the time though.

-Rod

Have you checked the hoses that go to the cannister?