Fails Emission Test

Ensure air intake system is not restricted.
Ensure engine is at normal operating temperature.
Ensure fuel system pressure is correct.
Ensure base timing is correct.
Check for correct PCV valve operation.
Check crankcase for gasoline contamination.
Test ISC actuator.
Test EGR system for correct operation.
Test purge control valve operation.
Ensure throttle position sensor has correct adjustment and resistance value.
Test operation of coolant temperature sensor.
Ensure exhaust system is not restricted.