1995 Escort 1.4 high fuel usage

My 1995 Escort seems to be using a lot of fuel lately. It has a 1.4 PTE SEFi engine. For the past few months I am only getting 20mpg round town. I checked the air filter and it is clean. I also checked the spark plugs but they are the correct colour indicating the fuel/air mixture is right. Could it be the oxygen sensor? Can anyone help?

I believe that is a 1.9 not a 1.4 in your '95..I have a 94 with 135,000
and just replaced the oxygen sensor a week ago. I also was noticing
poor fuel economy and pinging, replacing the sensor solved both
problems, Good luck, Barry

Have your emissions checked out. A bad catylitic converter could cause this.