Hesitation, Sag, Stumble

DEFINITION
Momentary lack of response as the accelerator is pushed down. Can occur at all vehicle speeds. Usually most severe when flrst 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". Testing and Inspection
^ Check for service Bulletins updates.
^ Check for correct EPROM.

SENSORS
^ Check TP 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) SENSOR OUTPUT CHECK". Chart C-1D Manifold Absolute Pressure (MAP) Output Check

IGNITION SYSTEM
^ Check spark plugs for being fouled.
^ Check ignition system ground, CKT 750.

FUEL SYSTEM
^ Check fuel pressure. Refer to "DIAGNOSTIC CHARTS/A-CHARTS/CHART A-7 FUEL SYSTEM DIAGNOSIS".Related Tests, Information and Procedures
^ Check for contaminated fuel.
^ Check Evaporative Emission (EVAP) control system for proper operation. Refer to "DIAGNOSTIC CHARTS/C-CHARTS/CHART C-3 EVAP CANISTER PURGE SOLENOID CHECK". Chart C-3 EVAP Canister Purge Solenoid Check
^ Check fuel injectors. Refer to "DIAGNOSTIC CHARTS/C-CHARTS/CHART C-2A FUEL INJECTOR TESTING". Chart C-2A Fuel Injector Balance Test

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 for intake valve deposits.