Sensor/System Checks

Check Heated Oxygen Sensors (HO2S). The HO2S should respond quickly to different throttle positions. If they do not, inspect the HO2S for silicon or other contaminates from fuel or the use of improper RTV sealant. The sensors may have a white, powdery coating and result in a high but false signal voltage rich exhaust indication. The ECM will then reduce the amount of fuel delivered to the engine causing a severe driveability problem.
Check for an Engine Coolant Temperature (ECT) sensor that has shifted in value. See TEMPERATURE VS. RESISTANCE table.
Check for proper operation of the Manifold Absolute Pressure (MAP) sensor. See DTC P0106: MANIFOLD ABSOLUTE PRESSURE SYSTEM PERFORMANCE under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 2.2L ION article.
Check for proper operation of the Throttle Position (TP) sensor. See DTC P0122: THROTTLE POSITION SENSOR CIRCUIT - LOW VOLTAGE or DTC P0123: THROTTLE POSITION SENSOR CIRCUIT - HIGH VOLTAGE under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 2.2L ION article.