Rough idle when cold due to upper intake manifold gasket leak on Mercury Mountaineer

TheĀ Check Engine Light will illuminate and the engine will idle roughly when cold. There are updated upper intake manifold gaskets to resolve the problem.

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Average mileage: 182,300 (158,000–206,600)
Engines affected: 4.0L V6, 4.0L V6 SOHC, 5.0L V8
4 model years affected: 1998, 1999, 2000, 2001
7 people reported this problem
1 person shared problem details
1999 Mercury Mountaineer- 5.0L V8206,600
High idle (approx. 1700 rpms)and check engine light came on. Had it diagnosed, shop said it was due to leak at manifold gasket. Idle increased to compensate for the leak. Repair estimate - $400 I was told in my case it is not a bad leak and can be delayed until it gets worse. I will wait.
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