I was driving north to Santa Fe from Albuquerque yesterday when I noticed the fuel consumption starting to change.  I was dramatically decreasing by about 1/3.

While I wasn't pushing the vehicle (65-70mph) I still could feel a decrease in pedal response as well.  It was still driveable but it felt like it lost its high end.

I wasn't using the Turbo at all and was running the engine between 3,000 to 3.500 rpm.

I have a Bentley manual but thought I'd ask for any feedback before I start snooping around on it this weekend.  While Chilton Manuals can help you troubleshoot a problem I don't see that with Bentley.

Any place to start other than the Spark Plug wires and the MAF?

Could it be a Fuel Filter?

(I've had the car about 5 months and have put 3,000 miles on it)

Thanks,

When this happened to me it was the cam adjustor sensor that went out first, but it was pretty much simultaneous with the MAF going out.