Lack Of Power, Sluggish Or Spongy: Sensor/System

Check the Crankshaft Position (CKP) sensor "B" for an internal short. See ELECTRONIC IGNITION SYSTEM DIAGNOSIS under IGNITION SYSTEMS in SYSTEM & COMPONENT TESTING - 3.1L CENTURY, GRAND PRIX & MALIBU article.
Using a scan tool, monitor Knock Sensor (KS) system for excessive spark retard activity. See KNOCK SENSOR under INPUT DEVICES in THEORY & OPERATION - 3.1L CENTURY, GRAND PRIX & MALIBU article.
If knock retard is above 10-12 degrees, disconnect the KS, and ground the sensor harness connector. Monitor knock retard on the scan tool, there should be no knock retard present, if knock retard is still present, replace the Powertrain Control Module (PCM).
Check the Exhaust Gas Recirculation (EGR) system for proper operation. See EXHAUST GAS RECIRCULATION under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - 3.1L CENTURY, GRAND PRIX & MALIBU article.
Check the air intake ducts for being collapsed, damaged areas, looseness, improper installation, or leaking especially between the Mass Airflow (MAF) sensor and the throttle body.