Mitsubishi Repair: 94 Eclipse Cold Start Stalling, throttle position sensor, gas mileage

Question
My 94 Eclipse sputters and stalls during a cold start. It operates better after it warms up, but sometimes runs sluggish. The dealer tuned it up a year ago, but it hasn't helped much. What's wrong. Oh, the Check Engine Light has come on and the dealer changed out the Oxygen Sensor. The light sometimes comes on, but goes out after a few days.  

Answer
Bill,
You may have a problem with your throttle position sensor.  Surprisingly, the dealer should know the exact problem what caused the check engine light came on.  A failing oxygen sensor usually would cause terrible gas mileage.  If your gas mileage was really bad before these problems were occuring, then your O2 senor could have been a problem as well.  

If your gas mileage was fine before the O2 sensor was changed, then the dealership most likely misdiagnosed your car.  If your check engine light comes on again, take your car to an AutoZone if you have one in your area.  They will read the codes off your car's computer for free.  My guess is that your throttle position sensor is faulty, or even your idle air control motor is starting to go bad.  
Good luck!