During P/S Operation (Aerio)

With wheels turned, check P/S signal circuit. See POWER STEERING PRESSURE SWITCH CIRCUIT CHECK under MISCELLANEOUS CONTROLS in SYSTEM & COMPONENT TESTING article.
Faulty spark plugs. See IGNITION CHECKS in BASIC DIAGNOSTIC PROCEDURES article.
Faulty ignition coil. See IGNITION CHECKS in BASIC DIAGNOSTIC PROCEDURES article.
Fuel pressure out of specification. See FUEL PRESSURE under FUEL SYSTEM in SYSTEM & COMPONENT TESTING article.