1994 Chevrolet Corsica

Engine Performance problem
1994 Chevy Corsica 6 cyl Two Wheel Drive Automatic 160000 miles

the problem is the vehicle stalls smoky black very consistently fails, I have already changed the MAP, oxygen sensor, valve JACK, the fail still exist in the vehicle, when the weather is cold the fail disappears until worm. I mean when the weather is cold not the car,

Can you feedback with this question, what can I do?
October 11, 2010.

Probable causes of an engine running rich are as follows: 1. Excessive fuel pressure can be cause by restricted fuel return line or defective fuel pressure regulator.
2. Defective Oxygen Sensors.
3. Leaking injectors and fuel pressure regulator.
4. Coolant temperature sensor out of calibration.
5. Restricted air intake system.

Oct 11, 2010.