Hi namster,
If the idling sped is too high, it would surge.
Did you try to adjust the idle speed?
Other possible causes are :
1. Vacumn leakages. Did you check for leaks at the manifold gasket?
2. Faulty Fast Idle Thermo Valve ( FITV). After the engine warms up, the FITV should close completely to reduce the amount of air going into the intake manifold.
3. Faulty IAC.
4. Insufficient coolant. If the FITV and IAC coolant hoses are clogged or does not have coolant passing through them the valve would not close fully.
EGR system would not cause surging.
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Thursday, August 26th, 2010 AT 1:40 PM