*Update*

Today i changed the O2 sensor which has made no difference whatsoever. I am still getting p1131 code, rough idling and hesitiation which is worse when hot. I have managed to get some live data info which I hope someone can shed some light on. At idle when cold the MAF reading is around 5.5 g/s and drops to around 3.5 - 4 when warm. short term fuel trim fluctuates between 0 and +35. however long term trim stays at 0! the pre cat sensor fluctuates between 0 and 0.2 and post cat goes upto 0.8. I have no idea what most of this means. Could bad coil, plugs or leads cause these problems?

Please help someone as it's driving me mad!!