That's a funky looking purge canister Welly. What model and year is it from?

One thing you could do is unplug the VSV at the engine so no purge gas enters. If the truck runs fine, it's the purge system. If not, it's something else. (You will get an MIL from unplugging the VSV)

Also, pull the B hose off and make sure it is not pulling vacuum when the VSV is unplugged. If so, it's the VSV. I believe the VSV at the engine pulses on/off to regulate the purge flow.

I'm curious about C, but not sure what it is.

94 4Runner, 5VZ-FE, A340H