Hesitation, Sag, Stumble

Definition:
Momentary lack of response as the accelerator is pushed down. Can occur at all vehicle speeds. Usually most severe when first trying to make the vehicle move, as from a stop sign. May cause engine to stall if severe enough.

Preliminary Checks
^ Perform the visual/physical checks as described under Diagnostic Notes in this section.

Sensors
^ CHECK: Throttle position (TP) sensor - check TP sensor for binding or sticking. Signal voltage should increase at a steady rate as throttle is moved toward wide open throttle (WOT).
^ CHECK: Manifold absolute pressure (MAP) sensor.

Fuel System
^ CHECK: Fuel pressure.
^ CHECK: Contaminated fuel.
^ CHECK: EVAP TVV operation.

Ignition System
^ CHECK: Spark plugs for being fouled, or for there being faulty secondary wiring.
^ CHECK: Ignition timing. Refer to "Vehicle Emission Control Information" label.
^ CHECK: Ignition system ground.

Additional Checks
^ CHECK: For correct ECM/PCM calibration (See Technical Service Bulletins).
^ CHECK: A/C operation. A/C compressor clutch should cut Out at wide open throttle (WOT).
^ CHECK: Engine thermostat functioning correctly and proper heat range.
^ CHECK: EGR operation. (California Emissions only.)
^ CHECK: Generator output voltage. Repair if less than 12 or more than 16 volts.
^ CHECK: Torque Converter Clutch (TCC) operation.