Hi all.
I have a query on our 2009 mazda 6 1.8 which I understand is broadly similar to the Ford duratec.

It has become a little jumpy on light throttle and has stalled a few times. No engine light till the other day after 2 hours on the motorway at 140km/h 90 mph.
Fuel consumption is a little higher than normal. From 7.5-8 lit/100 km to about 9. From 40 to 35 mpg.

I suspect an air leak but doused with deodorant (butane) and got nothing. When cold idle is a bit high but when warm settles to a low 600 rpm idle.
The pcv is a pig, the radiator seems to have to come out to fully remove intake manifold. I got a hose to it and it is opening when sucked and not allowing reverse flow.
The manifold I partially removed it, all swirl flaps are there and have no play. Some oily residue inside the manifold but not a layer and intake ports clean with no carbon.

When I changed the oil recently I went to top up with the engineering running and was surprised that the amount of gas escaping from the oil filler. Not to the level of spitting out oil but quite a bit. No visible crud gunk.

Over the last few oil changes in have noticed that the car will consume 4-5 litres between 20,000 km 12,000 mile changes.
Manufacturer allows upto 1 litre per 1000 km. No visible exhaust smoke.

Was serviced by the supplying Mazda dealer at 20,000 and 40,000km and 60,000 km.
I changed oil and filter at 80,000 km 48,000miles
I changed oil air petrol filters 4 plugs at 100,000km 60,000miles. Plugs were as new.
Oil and filters again at 120,000 , 140,000 and recently at 155,000 (it was a nice day and I had time!)
Fully synthetic oil castrol/total to the oil spec in the book each time.

I thought the blowby was a bit high and may be rings were gone on a cylinder so I pulled the plug each injector in turn which made no difference to blowby and not much to the engine idle either. I pulled each coil in turn which similarly did nothing to blowby but made the idle slightly lumpy.

I am waiting on a code reader to be delivered ( Halfords don't sell them here?!?)
Anyone any comments ideas or suggestions on the stalling or low idle.

Thanks Steve