Additional Checks

Visually and physically inspect the vacuum hoses for splits, kinks, and proper connections and routing as shown on the Vehicle Emission Control Information (VECI) label.
Check the intake manifold and the exhaust manifold passages for casting flash.
Check the exhaust system for possible restrictions. Check exhaust system for damaged or collapsed pipes. Check the mufflers for heat distress or possible internal failure. Check for possible plugged catalytic converter. See RESTRICTED EXHAUST .
Electromagnetic Interference (EMI) circuit can cause an engine miss condition. A scan tool can usually detect EMI by monitoring the engine RPM. A sudden increase in RPM with little change in actual engine RPM change may indicate that EMI is present. If a problem exists, inspect for high voltage components near the ignition control circuits.