Hesitation, Sag, Stumble

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

PRELIMINARY CHECKS
Perform the "Visual and Physical Checks" as described in Preliminary Checks. Testing and Inspection

FUEL SYSTEM
CHECK: Throttle Position (TP) sensor - For a sticking throttle shaft or binding linkage or misadjusted. Refer to Throttle Position Sensor / Adjustments for adjustment procedures.

CHECK: Manifold Absolute Pressure (MAP) sensor response and accuracy.

IGNITION SYSTEM
CHECK: Spark plug wires for being faulty.
CHECK: Spark plugs for being fouled.
CHECK: Ignition system for moisture, dust, cracks, burns, etc.
CHECK: Open ignition system ground.
CHECK: Ignition timing.

ADDITIONAL CHECKS
CHECK: For correct Engine Control Module (ECM), see Technical Service Bulletins.
CHECK: Generator output voltage.
CHECK: Exhaust Gas Recirculation (EGR) valve operation.