I own a 2005 Passat TDI wagon and for the past three months we've had a intermittent problem with accelerating. The problem usually occurs when trying to pull out on a main highway near our home. The car will struggle to accelerate to 30-40 mph, it's a 55 mph highway, and even with the accelerator pressed to the floor the car will not be able to climb above 40 mph. The problem has always gone away after parking the car and turning it off. Next time out the car runs fine with no acceleration issues. We took it to the local VW dealer and they replaced the turbo. Within days the problem recurred. We took it back and they replaced the valve leading to the turbo, or at least that's my understanding of the part they replaced. Within a week the same issue came up again. I took the car back to the dealer and they've now had the car for 10 days and I was just told they cannot find anything wrong. Said they are having their senior tech drive it home and night and they've found the issue very intermittent and no error codes are triggered. He said they've also done fuel pressure testing and found nothing wrong and they do not think there's anything wrong with the transmission. I have spent more than $3k replacing the turbo and valve and the problem still exists. My wife no longer is willing to drive the car with our kids since it's a really safety hazard when the problem happens and you cannot accelerate beyond 40 mph. A friend suggested this might be a good forum to get some possible explanations of what is wrong. Thanks in advance for any suggestions.