Nanda tbh when I've done it, I just get an exhaust shop to weld in a generic cat, whatever they use looks pretty similar to the stock cat.
But if you can, take the section with the cat out, and just shine a torch down it. You should see the honeycomb. If you shine a torch in from the opposite end, you should see the light coming through the honeycomb. If you see plenty of light coming through, it's not clogged. Could still be cactus but at least it isn't blocking the flow of exhaust.
The idle control valve really only affects idle, unless one of its hoses is split and leaking air in.
If you have a multimeter, check also that the signal from the O2 sensor is oscillating up and down in the 0-1V range. If it's sitting still, the O2 sensor is dead.
You can debug a bunch of the sensors on these cars by just unplugging them and seeing if the idling improves. AMM, engine coolant temp (2-pin plug in the head under the manifold), knock sensor (attached to block under the manifold), idle control valve, as well as the throttle position sensor (3-pin plug on the backside of the throttle body).
Try disconnecting and reconnecting them one at a time, and see if the car suddenly runs smoother.
In the videos it does sound like it is hunting idle a bit.
