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 careful visual/physical checks as described in "PRELIMINARY CHECKS". Preliminary Checks
^ Check for service Bulletins updates.

SENSORS
^ Check Throttle Position sensor sensor for binding or sticking. Voltage should increase at a steady rate as throttle is moved toward Wide Open Throttle (WOT).
^ Check MAP sensor. Refer to "DIAGNOSTIC CHARTS / C-CHARTS / CHART C-1D MANIFOLD ABSOLUTE PRESSURE (MAP) ". C-1D ~ Manifold Absolute Pressure Sensor (MAP)

IGNITION SYSTEM
^ Check Spark plugs for being fouled, or for faulty secondary wiring.
^ Check Ignition timing, using a "Scan tool".
^ Check Ignition system ground.

FUEL SYSTEM
^ Check fuel pressure. Refer to "DIAGNOSTIC CHARTS / A-CHARTS / CHART A-7". A - Charts
^ Check for contaminated fuel.
^ Fuel injectors are correct for vehicle.
^ Check Evaporative Emission (EVAP) control system for proper operation. Refer to "DIAGNOSTIC CHARTS / C-CHARTS / CHART C-3 EVAPORATIVE EMISSION CONTROL CANISTER". C-3 ~ Evaporative Emission Canister (EVAP)

ADDITIONAL CHECKS
^ Check engine thermostat for correct heat range and operation.
^ Check alternator output voltage. Repair if less than 9 or more than 16 volts.
^ Check Exhaust gas recirculation operation, Refer to "DIAGNOSTIC CHARTS / C-CHARTS / CHART C-7A"