I have a 1994 Mitsubishi Montero LS 3.0L.
It has had an idling problem for a long time but I dont know what it is. Most of the time it idles around 3000 RPMs when in park. When it is in drive it will not sit still, I have to keep my foot on the break or it will take off. It idles around 1500 RPMs then. Other times it wont idle at all, in drive or park. If I am driving and slow down too much it will stall. I have to keep my foot on the gas. I have observed no pattern to it at all. It seems totally random. I have had it put on a computer and nothing registered wrong. Also one mechanic thought it might be the Mass Airflow Regulator thing. The sensor that is just behind the air intake filter. He changed it and $400 later I have the same problem. Does anyone have a suggestion?
Clean or replace the Idle Air Control valve. Make sure there is not a physical problem, like a worn throttle cable or restricted linkage.