Hesitation, Sag, Stumble

WARNING: This page is about a different car, the 2004 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.

Checks	Action
DEFINITION: The vehicle has a momentary lack of response when pushing down on the accelerator. The condition can occur at any vehicle speed. The condition is usually most severe when trying to make the vehicle move, as from a stop sign. The condition may cause the engine to stall if severe enough.
Preliminary Check	Refer to Diagnostic System Check - Engine Controls . Refer to Symptoms - Engine Controls .
Fuel System Checks	Check for a restricted fuel filter or incorrect fuel pressure. Refer to Fuel System Diagnosis . Check the fuel injectors. Perform the following procedures: The Fuel Injector Coil Test Procedure-Refer to Fuel Injector Coil Test - Engine Coolant Temperature (ECT) Between 10-35 Degrees C (50-95 Degrees F) or Fuel Injector Coil Test - Engine Coolant Temperature (ECT) Outside 10-35 Degrees C (50-95 Degrees F) . The Fuel Injector Balance Test Procedure-Refer to Fuel Injector Balance Test with Special Tool . Check for water contamination of the fuel. Check the throttle position (TP) sensor for binding or sticking. The voltage should increase at a steady rate as the throttle moves toward wide open throttle (WOT). Inspect the operation of the mass air flow (MAF) sensor. Run the engine to normal operating temperature. Turn OFF all accessories and observe the MAF sensor at idle with a scan tool. If the MAF sensor reading is more than 3.5 g/s refer to DTC P0101 . Check the evaporative emission (EVAP) control system. Refer to Evaporative Emission (EVAP) Control System Diagnosis .
Ignition System Checks	Inspect the spark plugs for correct operation and good ignition system performance. Refer to Spark Plug Inspection .
Additional Checks	Check the Service Bulletins for any updates. Check the generator output voltage.