Originally Posted by mpaone
... does this part need to be replaced at all and could it cause drivability issues if there is something wrong with it?...
I'm not an expert on this, but it's certainly plausible that after 120k miles of wear & tear, plus your manhandling, the charcoal canister and/or the hoses attached to it might need replacing. The canister is used to "soak up" gasoline vapor rather than releasing those vapors to the outside air (this happens when refueling, and also when the temp goes up, letting the fuel tank internal pressure stay constant).
The ECU is programmed to "empty out" the canister by sucking outside air through the canister, carrying out the stored vapor and transferring it to the intake manifold. If the canister/tubing is disconnected/leaking, you could be getting too much air in through this route; if the canister/tubing is blocked, you could be getting less air than the ECU thinks.
I would think that you could test this by disconnecting the hose going to the canister at the purge control solenoid valve (this is up front) and trying to drive the car with the input to the valve blocked, then trying to drive the car with the input to the valve open to air. If one of those conditions keeps your problem the same, then that should be the type of problem you have.