I put a new AC 02 sensor in (111,000 on the old one). Gas milage with the old 02 sensor was 27 MPG at 65 MPH, 24 MPG at 72 MPH. Milage with the new sensor is 30 MPG at 65 MPH, 27 MPG at 72 MPH, and the shocker 21 MPG at 82 MPH (old 02 I could cruise at 100 and get 21 MPG). All on flat ground. Only took it out for a twenty mile drive. Does the 02 sensor take time to stablize the MPG? All the MPG readings are from the DIC which in our car has been very accurate. We used to get 30 MPG at 75 MPH. When we go for a drive it is not unusual for us to put on 400 to 900 miles a day, so a milage drop or increase of 2 or 3 MPG can cost or save us a good chunk of change.

ROD

Get a PCM to go with the mods to help stabalize the mpg and fuel usage by the engine?

Sorry to ask..are you talking the estimated fuel economy?

Im guessing so, which is usually off by a few.