Could be running too rich due to the following
Check the fuel pressure if its within specs with a fuel pressure gauge.
1. Excessive fuel pressure can be cause by restricted fuel return line
2. Defective Oxygen Sensors.
3. Leaking injectors and fuel pressure regulator.
4. Coolant temperature sensor out of calibration.
5. Restricted air intake system.
Tuesday, December 14th, 2010 AT 5:34 PM