Power Issues - 2002 VW Passat - 1.8T

[b1biker at aol.com]

Fellow listers I', hoping that someone out there has some experience with these cars; they are far to new for me to be driving. A very good friend of mine who lives in Colorado had been experiencing a loss of power in her car. They have changed ignition modules, plugs, fuel filter, and everyone keeps telling her that the car is fine. However, she says that she now has to downshift to maintain speed in the mountains and she never used to need to do that. I would suspect that the engine was just getting tired but she recently had some very bad luck and now has a different engine in the car and is experiencing the exact same problems. If anyone has any suggestions on where to look for the problem both I and she will be greatly appreciative. 
Thanks in advance for your assistance,
Gary Meier
88 5KSQ, 91 Passat