Engine Runs Rough On Deceleration

Check intake manifold vacuum. Vacuum should be more than 17.7 in. Hg at idle.
Check air filter element.
Ensure Engine Control Module (ECM) terminal voltages are okay.
Check fuel injection system operation.
Check Mass Air Flow (MAF) sensor.
Check MAF sensor element for contamination.
Check Throttle Position (TP) sensor.
Check throttle body for contamination.
Check for leaking fuel injectors.
Check EGR system, check EGR valve for sticking open and EGR solenoid for proper operation.