I purchased a used 2004 Passat TDI and drove it 1250 miles. The problem started about 300 miles into the trip. I would try and accelerate quickly and it would hesitate and shudder. When I let up on the throttle it would accelerate without the shudder. I thought maybe it was the fuel filter and added some condtioner to it, but this did not seem to help. The car ran smooth at 73 mph and I did notice a shudder once and while when climbing hills. The car has 56000 miles on it and I am not sure what mainenance has been done to it. Does the transmission need to be replaced?