The length of the intake manifold is adjustable: a switching linkage moves the flaps, and that linkage is made of plastic. An oil leak appearing at the intake manifold turns the plastic porous, and the linkage breaks.
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With a broken linkage the flaps do not move, which means the intake manifold stays in one position. The symptom is a noticeable loss of power and a fault lamp coming on.
The cause is therefore not the age of the linkage but the oil: until the leak is stopped, things end up in the same place again after a replacement. Repair kits are available on the market, but they do not deal with the leak that causes it.
What to check
- Accelerate at full throttle: a noticeable loss of power belongs here
- Shine a light on the intake manifold: a trace of oil around it is the cause
- Have the fault codes read and look for ones pointing to intake manifold adjustment