My 01 F-150 is about to hit the 70k mark. I have noticed that the mpg have been dropping off. Since I'm in California, I thought it was mainly the gas and the traffic here. I haven't been keeping as close an eye on it as I normally do. This last week I checked it and the highway mpg was down from 17.5 to 14.23 mpg. I'm going to replace both the pre-cat O2 sensors and check it again. The owner's manual says 100k, but I feel it's time now. I don't have an engine service light on. I'll post my results after the change.

Happy Thanksgiving everyone
Keep on Truckin