P0171, P0174

2004 Lincoln LS

Engine Performance problem
2004 Lincoln LS V8 Two Wheel Drive Automatic 95000 miles

I'm getting these codes. Car was riding great, all of a sudden the check engine light comes on, I get a code reader and I get codes P0171 and P0174. The car is now a little sluggish and sometimes seems to have no power. Help?
June 4, 2010.

P0171/P0174 Lean fuel condition could be caused by one of the following below: 1. Vacuum leaks
2. EGR and PCV valve.
3. Low fuel pressure.
4. Dirty fuel injectors.
5. Mass Air Flow Sensor.

Jun 4, 2010.