thought i would share - replaced the stock 3 wire O2 sensor on 91 100 today with 4 wire bosch #13275 (listed for 89 ford taurus). staight forward splice of 2 white and one black wire from factory harness with extra gray wire on new sensor to ground. no more "hitting the wall" while cruising and acceleration is much smoother and more responsive. waiting to see if any improvement in dismal gas mileage (more important now that a gallon of gas is more than a pack of cigarettes! ha!).
joseph