2005 chevy trailblazer_ls_ext
What exactly is this CC assembly you speak of?
I'll add my experience here.
I was having the same symptoms as the OP with my 2002 Envoy XL SLT. From reading Trailvoy, I was pretty sure it was also my catalytic converter. It was really starting to have major problems with taking off from stops and I've even gotten a better idea of what streets in my city has the biggest hills as my power would really bog down if I had to make it up an incline. For several weeks there I was driving in the slow lane.
I was able to find the catalytic converter on Amazon for $200... with free shipping. For the XLs make sure you get the CC assembly for the longer wheelbase, btw. Another $120 in labor charges with the local shop close to my neighborhood and my GMC Envoy now runs like a champ again.
Hopefully this helps somebody. I know I've gotten a LOT from this site in the short time that I've owned my Envoy, so hopefully I'm giving back a bit here.
Love the site!!!