Mechanics

ENGINE RUNS ROUGH WHEN COLD

2000 Mercury Sable

Engine Performance problem
2000 Mercury Sable 6 cyl Two Wheel Drive Automatic 130000 miles

My daughter's car runs very rough & stalls at start-up. It gets better after it warms up. A mechanic told us the engine code indicated a gross vacumm leak. He replaced all vacuum hoses and the air filter. It didn't help. Any idea what the problem could be?
Avatar
Nanaj
November 1, 2010.



Engine running rough or misfiring can be cause by the following: 1. Defective spark plug
2. Inadequate spark/coil, defective spark plug wire.
3. Lack of compression
4. False air leakage.
5. Faulty fuel injectors.
6. Insufficient fuel pressure.
7. Contaminated fuel.
8. EGR valve that is leaking.
9. Oxygen sensors.
10. Throttle position sensor.
11. Manifold absolute pressure sensor

Rasmataz
Nov 2, 2010.