Your gas milage seems rather low. I have a 92 190E2.6 with 80K miles and it gets 27-29 mpg on the highway and about 22-24 around town. I set my CIS a little rich (1 flat on the 3mm adjustment screw) which helped with cold start and running. The EHA current during closed loop changed from -1.5 ma to about -3.0ma. I changed my O2 sensor at 50K due to surging at idle and the result was a faster O2 response and a little leaner EHA reading. I used an O2 sensor for a 5.0 Mustang for $39.00 and just cut the wires and soldered the wire ends from my old O2 sensor. Works great and very easy to change.