Got a bit of an issues with my 09 5.0 s/c, light acceleration at around 1400-2000 revs getting a misfire, hard acceleration or just nursing it past this rev range seems to be ok, had it plugged in and got

P010B Air flow sensor B
P0420 catalyst system malfunction bank 1.

Tried a brand new air flow meter in bank B ( looking at the engine on the right) but still no difference. Anyone shed any light on these issues?

Did you changed the right side? From the WM.......

Cylinder arrangement
Specification
4.2 litre, 90 degree 'V', supercharged, petrol engine, twin overhead camshaft per cylinder head, 4 valves per cylinder
V8, numbers 1 and 5 cylinders at front of engine when engine is viewed from rear
Number 1 cylinder - right hand bank; Number 5 cylinder - left hand bank

You could well be right I was going off this I had off another member:

Click image to enlarge

Hope, if you switch the sensor, it wil work.
Good luck.

Also, check for a airleak in, somewere along the air intake.
Hope you do find something.
Piet

Any luck on this Sir?

Tried another new sensor in the other side and I think it’s sorted now. Difficult to tell 100% as it didn’t do it all the time

Good job, hope it works and stays that way.
Fingers crossed

Took the car for a good drive over the weekend, still has same issue. Would ‘P0420 catalyst efficiency’ give this sort of misfire / hesitation?

I dont know Sir, but Ill think best is to begin with any leaks in the inletsystem
( lean running ) en/or faulty oxygen sensors.