Sensor/System Checks

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.
Check for proper operation of the Intake Air Control (IAC) valve. See IDLE AIR CONTROL SYSTEM under IDLE CONTROL SYSTEM in SYSTEM & COMPONENT TESTS - 2.2L ION article.