Additional Symptoms Tests: Surges/Chuggles

Inspect the mass air flow (MAF) sensor for obstruction, contamination and damage. Refer to Mass Airflow Sensor/Intake Air Temperature Sensor Replacement .
Test the heated oxygen sensors (HO2S). The HO2S should respond quickly to a change in throttle position. If the HO2S do not respond to different throttle positions, inspect for contamination from fuel, silicon or the incorrect use of RTV sealant. The sensors may have a white powdery coating and result in a high, but false, signal voltage, which gives a rich exhaust indication. The ECM reduces the amount of fuel delivered to the engine, causing a driveability condition.
Verify that each injector harness is connected to the correct injector.

IMPORTANT: A vehicle with a camshaft actuator uncontrolled and wandering may experience an engine surge.

Start and run the vehicle until fully warm. Observe the CMP variation parameter while accelerating up to 1,500 RPM and back to idle several times. The CMP variation should indicate a value for 1-2 seconds, then return to 0 degree. If the camshaft actuator does not respond, refer to Camshaft Timing Drive Components Cleaning and Inspection (Fourth Design) .