Q: unstable Idle speed on 1995 Hyundai Accent

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Please I need probable cause or area to look at the problem. The engine Idle is very unstable sometimes it reach to 1500 rpm then later it goes down to 1000 or 900 rpm. i already adjust he throttle but still the same problem. no check engine light indicates.
(2) Answers
(1) Comments
First thing that I would inspect is the idle air control motor. It is the device that controls the speed of the engine idle and it sounds like it may be sticking. Are there any check engine lights on? if so, get those codes and that will also help you.
thanks for the response... one thing if Iam going to reset the ECU by unplug the battery cable which supply the ECU while the ignition switch is on. The problem will resolved temporarily but later around 10-15 kilometer running the problem again will occure you can observe the Idle it will increase slowly....You can also observe while shifting gear you can feel the engine speed will increase..
if your car is fuel injection then it is the idler valve, if its carburator then the carburator needs to be cleaned.