Ihave a 1990 EclipseGS 2.0 that has developed a cold start issue. It began 6 weeks ago after I replaced a starter. When cold it turns over fineand start to catch but willnot run. When it does finally start running it will only idle - if I step on the throttle it will die. After it warms up it is ok. I can heat the throttle body up and it starts fine. This only is happening when the temp drops below40degrees and the car sits several hours....overnight or at work 8 hours. When the air temp is back above 40 degrees it will start fine. It has no problem running when warm.Also - the check engine light is coming on intermittantly. I checked for vacuum linesall seems intact. No previous problem over last 2 years. Any ideas ?

 

Bad coolant temp sensor, when it goes bad it will make the car run vryr rich making it hard to start and fouling the spark plugs.

 

Thanks for the info-will check the sensor.