If you have a carburetor, there is a crew on the driver side behind the throttle cable it usually has a spring on it if you turn it to the right it idles up left it idles down If its a fuel injected motor idle is handled by the computer. There usually is a "base idle speed" around 800-1000 RPM. This normally doesn't need to be adjusted.
Have a look for carbon build up on the butterfly as well, this will influence idle too.
It could be a dirty air filter or a dirty throttle body.
probably a bad idle air controller.
the iac motor is faulty replace....(automatic idle control) easy fix 2 bolts and 2-3 wire connections.
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It probably means that one of your head or tail lights is about to go out. I have a Ford Taurus and my right blinker started blinking very quickly and within a week, my right headlight was out.
check for unhooked vacuum lines
Why is ford clock fast? why clock fast in vehicles
i don't know if it is a Ford thing, but my dodge did somewhat the same thing... my blinker would flash very fast on the dash and it turned out that my bulbs were out in the rear (maybe that is the problem and your brake lights are connected). When the bulbs burn out the circuit is shorted.
how fast is a ford v8
Need to know year and type of car including what motor please.
it idles quickly to save as much fuel, energy, oil, etc. as possible
It goes fast