I have been driving my ED fairmont, and its been chewing the fuel over the last two tanks..

I usually put in 40 bucks worth and it will last me until the following tuesday, but lately i have been doin only around 150k's to $40 worth..

My trip comp used to always be around 14.5-15.5l per hunders, and now its at 17.8

I should mention i put in some injector cleaner a few weeks ago, would this have made a difference?

It may have made a different, your blocked injectors could have caused the "better" fuel economy, but in the process make the car run lean and hotter then it should. Thus it could have fried some sensors. I would check the O2 sensor if it hasn't been replaced before, check for any vacuum leaks if the hose on the MAP sensor is still connected. Also have you been using the air con more then usual?

phong =P~

crap fuel buddy,,some times i can go 2 weeks with out topping up and other times i have to top up inbetween.

i usualy find the more fuel smells the better it is as its fresher,,if you can barely smell it then its off.

Check the condition of your ignition system components, H.T leads, dizzy cap & rotor, spark plugs, ign coil for cracks, timing, etc. When was the last time you changed your fuel filter???