1999 Chevy Prizm slight hesitation

1999 CHEVROLET PRIZM
87,500 MILES • 4 CYL • AWD • AUTOMATIC
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MOWGLI84
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I have replaced the coil packs, gave it a tune up, replaced the universal part near the catalitic converter, and the car still hesiitates near 60 mph, used to hesitiate at 45 mph before all these repairs.
The car rattles still when cold.
Jul 27, 2009 at 11:02 PM
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RASMATAZ
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Hesitation can be caused by the following:

Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires
Jul 28, 2009 at 1:31 PM