gas mileage 2001 forester L

I have 96k miles on 2001 forester L 4wd manual transmission. The check engine light came on and I have replaced the catalytic convertor, O2
sensor and my gas mileage is still very erratic. No more than 300 miles to a tank and average 270. There has been a decrease in gas mileage since the check engine light. 85% of my driving is highway. Suggestions?
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I would suggest you reset the ECM to reset the engine parameters to the factory default settings. The unit learns from your driving habits so it will take several tank fulls to establish a YOUR parameters. If you chose to drive for millage then take it easy for a few tank fulls. After you get several hundred easy acceleration starts into the system you should be good. If you red line it on occassion you still will get good millage overall because you will have many hundred easy launches and only a few hard launches. Some of us reset the ECM every so often. Do this by removing one baattery cable for an hour or so or you may speed up the process by holding the brake pedel on for a minute or so. This discharges the unit quicker. Let us know how you do. Ed
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