I tuned up (at Ford Dealership (good friends)) about two weeks ago and no sensors were replaced. I do not get any EEC code either. Would the computer tell me (via code) that the O2 sensor was out. It did with the ECTS code 21, but I fixed that by a tune-up. Before the engine ran so cool that it stayed in closed loop. 28 would be great but I think I'm getting about 15 to 16 MPG.

Andy