90 Olds C utlass very bad idle

[crazyoildude]

90 oldsmobile Cutlass 3.1 has an idle that goes up and down and sometimes stalls when in drive..Car does not have a miss or rough idle just eratic most of the time.. Also it seems to be running rich and he said the check engine light came on for a while earlier in the day.. Car is pretty far from here and i am trying to help him over the phone..He says the check engine light is off now..Any ideas as to what could be wrong with it..
I put rebuilt fuel injectors and did a complete tune up about 1 year ago he just drives about 10 miles every day at low speeds.. Oil is changed with 5w30 every 3000 miles..

 

[CourierDriver]

go for the marvel mystry oil,,,its a biggie in here

 

[2oldtommy]

Try a bottle of "Techron Complete Fuel System Cleaner" as the first step. Any auto parts store has it. FWIW-- Oldtommy

 

[beast3300]

Have him do this with a paperclip. You can get a code to see what the computer thinks is wrong.

http://www.troublecodes.net/GM/

This will aid in going the right direction to see what to do.

 

[Michael_P]

Sticky EGR. Pre OBDII so it will clear itself once it is fixed.

Bad EGR's tend to goober up the intake manifold gasket on 3.1's in short order since there is not enough airflow to keep the manifold cool with all that exhaust getting in there. You should be okay though. But just in case there is an issue afterward (provided this is the issue), check there next.

 

[Texan4Life]

maybe a vacuum leak?

to check how bad it is running rich pull the dipstick and have a smell.. gas then yeah your running real rich for one reason or another. my brother has the 3.1 in his grand am and went 17k miles on gas diluted super tech syn oil. It had a big vacuum leak.

when cars get to be 20 years old, vacuum lines and fittings turn to dust if you look at them wrong. dont ask how i know.

michael might be onto something cuz I had my check engine light come and go with a EGR code before. I put in a new valve and while doing so found one of the two egr tubes in the intake manifold completely blocked.

to be sure though getting the code(s) would be best.

 

[mechtech2]

Check and repair all vacuum leaks, esp the PCV system. Allines and the intake.
Clean the throttle body real nice. Then the Idle Air Motor , if necessary.