Hi new to this but after buying my xtrail in February this year it's been a nightmare! Power loss with no fault codes or warning lights, when reaching a hill felt like you were towing a train behind. I replaced the suction control valves (£200) no joy, various engine, injector and turbo cleaners but still no joy! Car pulled on flat till 3500 revs then held back. Tried to trade car in but best offer I had was £1500 and had limited funds to add so that was a no go. Spent hours searching the net but still could not find a fix. Anyway after getting so pissed off I adopted the attitude if "what the hell" and began attacking the car with various spanners, and found a fault so simple I could kick myself (Iv spent around £500) the mass air flow sensor was dirty so removed and cleaned with ecu cleaner, replaced and...... No better I then removed the housing the the maf sensor fits in, the whole pipe and top of the air filter box. Inside there is a mesh that prevents debris before it gets to the air filter. This was blocked by soot and flys etc so a wash of the whole thing with soapy water (left to dry thoroughly) then replaced. The car now pulls fantastic and is the acceleration is smooth through to 7000 revs. I hope this helps someone