Hi all, i recently bought a disco 2 automatic (2003) and its great, however when i was pulling onto the duel carridge way yesterday and required a few more revs, as soon as i stepped on the accelerator it began to stutter, as in accelerating then dying the accelerating and dying again until i removed my foot. now the car is due a service soon and i did check the air filter which does have a fair bit of oil in it and was wondering if this could be the issue and if it was related to the black smoke coming out the back at the same time. good thing is i have a 6 month warranty so im eager to get it sorted for free. any help would be greatly appreciated.