# Truck Lunges and has a Rough Idle

**URL:** <https://community.cartalk.com/t/truck-lunges-and-has-a-rough-idle/3851>\
**Category:** Maintenance/Repairs\
**Created:** [August 29, 2007, 6:47pm UTC](https://community.cartalk.com/t/truck-lunges-and-has-a-rough-idle/3851 "2007-08-29T18:47:51Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Hwood563](https://avatars.discourse-cdn.com/v4/letter/h/46a35a/32.png) [@Hwood563](https://community.cartalk.com/u/Hwood563)\
**Post date:** [August 29, 2007, 6:47pm UTC](https://community.cartalk.com/t/truck-lunges-and-has-a-rough-idle/3851/1 "2007-08-29T18:47:51Z")

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I recently Bought a 1989 Ford F150 4x4 and when the truck is stopped or in idle it wants to lunge forward. The battery gauge jumps back and forth as well. The truck has a fairly new battery. I have replaced the spark plugs/wires/dist. cap/ and rotor button and this did not help. The truck runs great down the road and will run good for a while after stopped but then starts the rough idle after a few seconds. Any Ideas??

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**Author:** ![Roadrunner](https://avatars.discourse-cdn.com/v4/letter/r/d2c977/32.png) [@Roadrunner](https://community.cartalk.com/u/Roadrunner)\
**Post date:** [August 29, 2007, 8:52pm UTC](https://community.cartalk.com/t/truck-lunges-and-has-a-rough-idle/3851/2 "2007-08-29T20:52:50Z")

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Have a look at one of these:

Intake air (vacuum) leak  
faulty fuel pump  
Faulty IAC (Idle Air Control) motor.  
Or perhaps an emissions fault.