Every Eagle manufactured after 1980 has an oxygen sensor in it.  Your Eagle oxygen sensor helps your engine to run efficiently and to produce as few emissions as possible.  In every vehicle, there is a specific ratio of air and gas that is considered perfect.  Less air in the ratio causes what's considered a rich mixture.  More air in the ratio is called a lean mixture.  Both create pollutants, while a lean mixture may also cause poor performance or damage the engine.  The oxygen sensor detects these changes in the ratio of fuel and air.  It sends the data to the engine computer, which then adjusts the amount of fuel to balance out the mixture once again.  If your oxygen sensor fails, your engine's computer will be unable to sense the air/fuel ratio.  The only thing it can do at this point is guess what the ratio is.  This is why a broken oxygen sensor can result in hesitation, poor acceleration, surging, and overall poor engine performance.