Low / uneven idle problem can cause by a lot of components.
Dirty air filter
Dirty injectors + o-rings
Vacuum leak at intake manifold and vacuum hose.
Bad Idle Air Control Motor (IAC)
Low compression (170 psi + is OK)
Start cleaning and repair these trouble spots and see is there any improvement.
====
For more advance DIY'er then you may try this.
Use a can of Berryman carburetor clean to locate the vacuum leak.
SEE SAMPLE PICTURE HERE
This is a 20-30 minutes job.
Vacuum leaks can occur in following locations.
Intake manifold AND/OR vacuum lines.
Intake manifold is not accessible unless the engine head if off.
You can still check the potential leak by spraying some Berryman near the intake manifold.
Listen for rpm increase after you introduce the Berryman (FUEL) at idle.
Do the same starting from the brake booster unit (the round unit) on the drive side fire all.
Carefully listen for increase of RPM right after to spray the Berryman to the potential vacuum spot.
Get a friend to HEAR the ROM increase or monitor for RPM on the tech.
DO NOT AIM the Berryman into any heat source.
PLEASE RATE my answer if it is useful to you.
Some air coming thru in inlet manufold. Check hoses.
It can be issue
with IAC( idle air control valve) causing the problem.
There
are many other possibilities causing these idle issues. Engine idles rough.
There
are few help links with solutions to troubleshoot such idle issues.
I
suggest you refer the link below and follow
its troubleshooting details:------
Click
the link below:-----
-----------
http://schematicsdiagram.blogspot.in/2012/03/stumbling-and-stalling-at-idle-after.html
------------
http://technoanswers.blogspot.in/2012/01/1999-ford-f-150-idles-rough-and-quits.html
---------
http://repairhelpcenter.blogspot.com/2012/01/engine-stumbles-coming-off-idle-when.html
------------------
http://schematicsdiagram.blogspot.com/2011/12/erratic-idle-on-car.html
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Cold start problem and vehicle shudder around 2500 to
3500 rpms
----------
http://repairhelpcenter.blogspot.com/2011/12/low-idle-when-cold-out-side.html
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http://technoanswers.blogspot.com/2012/10/gmc-sonoma-stalls-and-idles-low.html
--------
http://schematicsdiagram.blogspot.com/2011/12/gmc-idle-air-control-iac-valve.html
-------------
http://repairhelpcenter.blogspot.com/2011/10/1996-camry-intermittent-engine-failure.html
------------
http://repairhelpcenter.blogspot.com/2011/10/engine-quits-at-idle.html
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http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html
---------
High
Idle Problem
http://repairhelpcenter.blogspot.com/2012/10/high-idle-problem.html
-------
http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html
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http://technoanswers.blogspot.in/2012/02/idle-flair-is-noticed-on-car-rough-idle.html
--------
http://technoanswers.blogspot.in/2012/02/high-rpm-in-neutral-inconsistant-high.html
-------
http://schematicsdiagram.blogspot.in/2012/03/vehicle-stumbling-at-idle-and-shows.html
----------
http://technoanswers.blogspot.in/2012/03/rough-idlestaling-and-erratic-shifting.html
-----------
http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html
---------
These
details will help.
Thanks.
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Just started? When it's warm? All the time? What are the conditions; be more detailed in your describing the problem.
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