I have Honda Accord (2006 UK model), and it runs perfectly as long as it is driving below 700m (above sea level). I live in London, and like to take long road trips through Europe. Hover, I am faced with a really strange problem: When my car gets over 700m it is starts to behave really, really strange. Every time I would start from a stationary position, or if I would to shift down whilst in motion, the car completely loses power. I cannot get it to go over 1500RPM (or so), it bellows thick dark smoke from the exhaust, and picking up speed becomes almost impossible challenge. I was able to find a "hack" to make this a bit more bearable. I would have to get the car moving then very quickly release accelerator pedal, then press it hard again when I feel the car slowing down. After few of these "pumping" actions, the car would start to drive more or less normally, as long as I do not shift down. I have tried to take the car to the garage, but it came out clean. Some garages came out with different theories, but they felt more like expensive guesses. As you would appreciate this is not something I can easily replicate. There are only four roads higher than 700m in Britain, and all are in Pennines or Scotland. Any ideas anyone?