Q: high idle around 3000 rpm when i start car when cold for about a minute then drops to 700 rpm, then it idles up and down in park

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when I start the car, it idles at 3000rpm for a minute then drops to 700rpm, then it will idle up and down in park or at a stop light and sometimes it stalls. it also seems to accelerate on its own while driving at any speed. I replaced the tps and iacv and cleaned the throttle body and still have the same issues. cant find any vacuum leaks. throttle body plate is not bent and cable is good.

My car has 80000 miles.
My car has an automatic transmission.

Although you replaced the idle control valve (ICV), a faulty or blown fuse in other electronically controlled systems can cause the IAC motor to malfunction, leading to a higher than normal engine idle speed. Other possible causes of a high idle include vacuum leaks, EGR system malfunctions, malfunctioning oxygen sensors, dirty fuel injectors, fuel pump malfunction, faulty spark plugs, a faulty mass airflow sensor, a malfunctioning throttle and, rarely, a PCM/ECM malfunction. With regard to vacuum leaks, on a fuel injected engine a vacuum leak will cause a high engine idle as the engine’s oxygen sensor detect the extra oxygen entering the engine through the vacuum leak. The newly lean (too much air relative to fuel) status will result in the engine’s computer pumping in additional fuel, resulting in an abnormally high idle. A malfunctioning throttle system can cause both a high idle as well as an engine stall. A dirty air intake or cracked air intake tube is often the culprit. If you desire that this high/inconsistent idle problem be diagnosed by a certified Mechanic, dispatched by YourMechanic right to your location, please request an engine idle speed diagnostic - high idle and the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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