Hi all, I am disapointed that nobody really who has had this severe problem has given a solution. I've found myself in the very same position for months now but with my wife in a far away hospital, it just recently became critical. I too changed the air filter, fuel filter etc. All to no avail. I had a strange rattling sound from the front end of the exhaust and an awful lot of water spitting out the back box so I took my car into my local garage and had the middle and rear sections of the exhaust changed, but still no cure. I asked them what they thought the problem was and they answered; "You didn't pay us for that!" I was supremely unimpressed. My car rev'd OK in neutral but stick it in gear, drive and you can't get above 2500 revs or at most 30 mph - worse on hills. It seemed the car had kangaroo petrol. The harder you pushed the accelerator, the worse the problem. The engine was choking itself. I am super annoyed though, not just that an obvious solution I couldnt find or that a definitive solution hadn't been posted here, but at the garage who replaced most of my exhaust, as the problem was the catalytic converter; not a million miles, just a few inches in fact, from the parts they replaced. My M.O.T. 30 day window opened up today and not only has my car now had this long term problem fixed but also a new M.O.T. I don't know if you have similar or identical symptoms to mine but if you do, please don't waste money on filters, plugs etc. or a new back box, mid exhaust section etc, try the cat. Good luck! ;) If only someone had posted this before, I'd have saved a fortune. I hope I can save you one too.