take a look in live data at engine temp as it could be causing an over fuel,also you need to take a look at fuel pressure as not enough pressure will cause the fuel to dribble into the cylinder and not a nice spray/atomise as well as checking the exaust/cat for blockage a quick test of the exhaust i sometimes do is to remove the o2 sensor and see if it fires up, air
filter??
ps i had a v40 doing exactly the same last year it had had loads of new parts fitted by a few different garages but none had checked fuel pressure/delevery and it turned out to be the filter blocked
hth martin