How many Oxygen Sensors does a '94 Corolla have? on 1994 Toyota Corolla

I had a tune up done about 2 months ago also the clutch changed... The car is now using way more gas then before so I'm trying to figure out things that I can replace to make the fuel economy better and was told this could help a great deal. Any other suggestions would also be extremely helpful! Thanks :)

Asked by for the 1994 Toyota Corolla