Rough/Unstable Idle: Carbureted

Ensure idle adjustment is correct.
Ensure idle-up system correctly responds to accessory load.
Verify vacuum hose routing is correct and that there are no vacuum leaks.
Check vacuum choke break diaphragm.
Ensure fuel level is at specified mark on carburetor sight glass.
Check PCV operation by clamping hose shut. If problem discontinues, replace PCV valve.
Check EGR operation. Ensure valve closes fully.
Verify ignition timing is correct.
Verify duty (mixture control) solenoid operation is correct.
Check anti-diesel system for correct operation.
Ensure vent switching valve activates when ignition is on.
Check throttle position sensor adjustment.
Check coolant temperature sensor operation.
Check thermostatic air cleaner operation.
Perform cylinder balance test to determine if problem can be isolated.