I haven't been getting great mileage from my 1999 Mercury Mystique. I get 24 mpg no matter how I drive. It gets 24 mpg on the highway and in the city. I'm slowly getting the regular maintainence done right now. I've changed the fuel filter, going to change the thermostat and get the ATX flushed. I read that the oxygen sensor is good for 160 000 kms. The car is at 158 600 kms so should I change it? As it looks original. I tried to look at the sparkplugs but I'm not sure how to remove the spark plug wires. My Haynes manual doesn't help in that detail. I tried to remove one but didn't pull really hard as I didn't want to damage it. Any suggestions?
