95 chevy g20 idles too high, how do I turn idle down?

First is all always write down the codes you have present, it helps in closing down on the problem. I am assuming you have a 95 Mazda Milleinia

1. Start and run the engine and monitor the oxygen sensor signals and see if this sensor has bad readings still. Check for an open or shorted wire between the sensor and the Engine Control Module (ECM) if the signal is dropping out.

2. Listen for an exhaust leak in the area of the oxygen sensor, the leak could allow oxygen in to the exhaust and skew the sensor readings.

3. Inspect the ECM and ECM connector for signs of something that has been spilled on the ECM. Is the engine idling too high or too low then check this:-
1. Unplug the idle air control valve and turn the air bypass screw in to see if it will idle down. If it will idle down, adjust the idle speed to around 500 RPM's and then plug the idle air control valve back in.

2. If it still idles high, remove the air boot from the throttle body, block the air bypass ports with duct tape, hook the air boot back on and start it. This should make it not idle at all or just barley idle. If it does, the problem is in the idle air control valve.

3. If blocking the air ports doesn't cause it to idle down, the throttle plate must be sticking open. Clean the throttle plate really good and back the throttle stop screw off and then see if it idles down.

4. Verify the coolant level is not low and that coolant is circulating through the idle air control valve. Tech Tips: This idle air control valve is two valves in one. It is a fast idle thermo valve on one side and a duty cycle idle air control valve on the other.

I’m happy to assist further over the phone at https://www.6ya.com/expert/uttamjeet_2f3adc18600f8ede

A temp sensor out of range giving a false cold reading can cause high idle . A MAP sensor can also cause high idle by advancing the timing resulting in higher idle .

This problem does not sound like a tps, It sounds more like the idle air control valve. It controls your idle by varying the amount of air at idle,If it is not working it can cause the problems you are having

Have you tried to adjust the idle itself to bring it down? The adjustment should be right on the throttle body where the gas pedal is connected to the throttle body. There should be a screw that will allow you to adjust the idle up or down. If you loosen the screw it will take your idle down

I can be problem with IAC valve or motor,or there can be vacuum leak issue it its dirty Idle control valve or problem with dirt build up in throttle body.Click this link below and follow step by step troubleshooting:-----http://whatisbyme.blogspot.in/2012/05/high-idle-on-chevy-blazer.html
---------------this should help.Thanks.

You can either try cleaning the idle air control valve or you can replace it.Afterwards you will need to reset the computer by disconnecting the ground cable on the battery for 30 seconds.

I recommend checking the EGR valve first as GM cars and trucks of this era are famous for small ckunks of carbon getting lodged in the valve seat and holding the valve open causing rough idle and general undriveability.

replace your oxygen sensor

THAT SOUNDS LIKE A BAD VACUUM LEAK. IT SHOULDN'T COST MUCH TO FIX. IT MAY BE JUST A "HOSE" REPLACEMENT.

intake vacuum leaks or bad wires and plugs.