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Q: the car revs high and at stop signs while slowing down then idles down suddenly and sometimes stalls, whats the cause?

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ive replaced idle control valve, egr solenoid, and cam sensor, replaced with used parts, map sensor maf, sensor, throttle position switch, egr valve proved to be good, found no vacuum leaks in hoses, pcv and hose was good? im running out of ideas? questioning cam senso,r,cat converter, possible evac problem? kinda grasping at straws now

My car has 122000 miles.
My car has an automatic transmission.

The engine intake manifold seals or the intake tubes between the mass air flow sensor and the throttle body may have a leak that you cannot hear, but could be found using a smoke machine designed to find the leaks. However, first, I would recommend having the engine’s computer scanned for any codes before checking for vacuum leaks. This can be done by you or by a mechanic.

A certified technician, such as one from YourMechanic, will have a smoke machine or some other type of vacuum leak detector to diagnose your revving and idling issue. There are some electronic detectors that may work as good as the smoke machine that may help in this case. After diagnosis, they can recommend a repair to have this issue resolved.

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