# Unstable idle

**URL:** <https://community.cartalk.com/t/unstable-idle/13526>\
**Category:** Maintenance/Repairs\
**Created:** [May 2, 2008, 12:31pm UTC](https://community.cartalk.com/t/unstable-idle/13526 "2008-05-02T12:31:55Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![jimmy\_d](https://avatars.discourse-cdn.com/v4/letter/j/4491bb/32.png) [@jimmy\_d](https://community.cartalk.com/u/jimmy_d)\
**Post date:** [May 2, 2008, 12:31pm UTC](https://community.cartalk.com/t/unstable-idle/13526/1 "2008-05-02T12:31:55Z")

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92 mazda miata starts and runs good but when stopping and engaging clutch, the idle  
  
 speed drops from 800 to 300 and back and  
  
 forth several times ,then levels out. HELP

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**Author:** ![VDCdriver](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/vdcdriver/32/30_2.png) [@VDCdriver](https://community.cartalk.com/u/VDCdriver)\
**Post date:** [May 2, 2008, 1:07pm UTC](https://community.cartalk.com/t/unstable-idle/13526/2 "2008-05-02T13:07:36Z")

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Check your idle air control motor.

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**Author:** ![Loafer](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/loafer/32/28_2.png) [@Loafer](https://community.cartalk.com/u/Loafer)\
**Post date:** [May 2, 2008, 1:20pm UTC](https://community.cartalk.com/t/unstable-idle/13526/3 "2008-05-02T13:20:26Z")

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throttle postion sensor or a vacuum leak could also cause that.