Had this huge problem and recently with severe power loss on my 2007 petrol caddy which took several months, much head scratching from numerous mechanics and lots of $$$$. I thought I would pass on my experience that in the hope it will help someone from the pain. I use my caddy daily for my work as a self employed electrician, I have had the vehicle for the last 5 years and in the main has been reasonably problem free. I started experiencing a gradual power loss when accelerating or struggling to get up banks, the issue steadly got worse till at its peak it would not rev past 2500rpm. I had the vehicle serviced and tested and the first bunch of mechaics tried many things in their box of tricks, including replacing map sensor, smoke tests, compression tests, fuel flow tests etc etc, nothing worked. The next stage was off to the main VW dealer to get it on the diagnostics, they found fuel filter was in need of replacement (so much for the service and previous mechanics), suspected the exhaust sensor or perhaps blocked injectors and suggested I put some cleaning agent through to try and clear any blockages. Tried that for several weeks and again no improvement. As the vehicle was used daily it was hard to find the time to book it in but eventually I had a small window and it went into the dealer end of October for a few days. After several hours of testing they were convinced the fuel pump in the tank was running at low pressure so $2000 later and a part from Germany it was replaced. No that wasnt it either so more diagnostics and low and behold it ended up being the Cat Convertor, again another $3000 and a wait for the part from Germany and yes it appears to be running ok so eventually got it back on 28th December so a whopping 3 months off the road and $5k plus the previous stuff that was done by first mechanics another 1.5k oh and before I forget timing belt chage prior to that so its been a big expensive year. With the benefit of hindsight I would not have spent so much on such an old vehicle but at what point do you stop, buying another vehicle could be buying someone elses troubles at least I now know whats been done to mine and I look forward hopefully to a few more years trouble free motoring. Hope this helps someone, wish I had found this forum first!