Engine Runs Rough On Deceleration

WARNING: This page is about a different car, the 1997 Mazda Millenia. However, it is still accessible from the selected car via links, so may be relevant.

Verify idle speed is correct.
Verify correct throttle body dashpot adjustment.
Check coolant thermosensor and throttle position sensor.
Check bypass air control valve or IAC valve for malfunction.
Check fuel pressure regulator.
Check HO2S operation.
Check throttle position sensor and closed throttle switch.
Check airflow sensor operation.