2002 s-type 3.0 v6 no power over 4000rpm

Hi I have a 2002 s-type 3.0 v6 automatic. 

I'm having a problem where the car will not accelerate over 4000rpm, it's like it hits a wall and it will very very slowly speed up with the engine revving, kickdown it will go to 5400rpm and same thing, engine revving but speed barely going up. 

Under that rpm range it seems just fine. 

I got a code for P0430 catalyst bank 2 below threshold. I reset the code, no idea how long its been there I've only had the car a week. Obviously the car behaves the same but the check engine light never came back? Even after 2 hours of driving. 

Here is a link to a video when I press full throttle 

As you see the revs go up but the speed barely changes at all, it feels like it hits a rev limiter. 

It will do this in any gear, if i manually put it into second, accelerate hard once it gets over 4k rpm barely no increase in speed. 

Any ideas? Would a bad catalytic converter cause this or is it a fault with something else? As I said so far the engine light hasn't come back on and no more codes has come back up. 

Update: forgot to add, the left tailpipe which I believe runs to bank 2 smells quite strong, kinda like unburnt fuel i think. The right tailpipe has very little smell.