Thought I would start from scratch.
Got code reader today and plug in to find the above.
301 and 304 misfire in 1 and 4
P0420 Catalyst System Efficiency Below Threshold (Bank 1)


What is the cat 1?
Is that my cat kaput or is this my 02 sensor playing up?
Is this what is causing the misfire or is this in addition to the misfire or is the because of the misfire?
Live data and freeze data I can put up too if it would help.
So far
Ignition coil changed
Plugs changed
Fuel Pump changed
FPR changed.


This has only been occuring since a water pump change of which the only thing removed was exhaust manifold