2000 Low Idle

2000 Intrepid, base model, base engine (2.7) 108k miles. For the last 20k miles or so when I come to a stop, the idle drops to 4-500 rpms and the oil light comes on. If I shift to Neutral, than back to Drive, the idel comes up to 6-700 rpms. If the A/C is on, no problems, the car idles at ~600 rpms.
K&N air filter sin 20k miles is the ONLY mod I've done.
It's not throwing any codes. Pulling the battery overnight to reset the computer doesn't seem to help. Everythign else is fine, power and mileage are unaffected. I run Seafoam or MMO thru everyt 5th tank or so. It is due for a battery, but the charging system check out fine.
Any comments or suggestions welcome. Help!

Flattaop in AZ

there are a couple of things that could be wrong: 1) you have built up carbon on your throttle body, you can get some carb cleaner, take your intake snorkel off and clean out any carbon built up around it. The second thing, if you have a weak battery, though the charging system may be fine, the battery could be weak to the point that it can affect your idle. If your battery is more than 3 years old, time for a new one; especially since you live in the desert, batteries go quickly in that hot climate.

there are a couple of things that could be wrong: 1) you have built up carbon on your throttle body, you can get some carb cleaner, take your intake snorkel off and clean out any carbon built up around it. The second thing, if you have a weak battery, though the charging system may be fine, the battery could be weak to the point that it can affect your idle. If your battery is more than 3 years old, time for a new one; especially since you live in the desert, batteries go quickly in that hot climate.

Thanx for the ideas.
I've had the stock airbox off all the way to the intake last year, cleaned it out with carb cleaner. It looked pretty good, a little black carbon looking dust, but no buildup I could see.
Replaced the battery this weekend (what a PIA that was) and no change, well, _maybe_ ~100 rpm change, but idle coming off the freeway is still rock solid at 500. Kick it to neutral and back to drive, idle sets back to ~700. <sigh>
Factory battery went 4 years 11 months, no complaints here.

Any opther ideas? 3K mile trip coming up and I want NO problems when I'm out in the middle of gawdawful nowhere. Love hte car otherwise.

Flattop in AZ

I believe your IAC (Idle Air Control) motor might be getting weak. It's not faulty that it would set a code, but it could be weakening. That or the drivers that control the idle are out of parameters. Go to a shop that can test all that and go from there.

I believe your IAC (Idle Air Control) motor might be getting weak. It's not faulty that it would set a code, but it could be weakening. That or the drivers that control the idle are out of parameters. Go to a shop that can test all that and go from there.


Excellent, I'll start there. If the IAC fails or weakens futher (assuming that's the problem) will it affect normal running anytime other than idle?
I ask because I may not have time to get it checked before I split for a road trip. Thanx in advance....


Flattop in AZ

If you IAC is getting weak it'll cause problems in how the motor runs and could also possibly set a code.