For 1990-2009 cars

1. Clean the intake manifold mating surfaces.
2. Inspect the intake manifold for damage.
3. Inspect the intake manifold for cracks near metallic inserts.
4. Inspect the crankcase ventilation passages in the intake manifold face for blockage.

Caution: Refer to Safety Glasses Caution in the Preface section.

5. Clean the crankcase ventilation passages with compressed air, if necessary. Use a maximum of 172 kPa (25 psi) of air pressure.
6. Replace the intake manifold, as necessary.