Rough idle cars in general

No, it's not a sensor. The engine computer controls idle speed by an "actuator" called an IAC -idle air control -motor or valve. It sits right on the throttle body where the air hose, the big boot, connects to the top of the engine. It controls the idle air passage-smaller air passages besides the larger throttle plate opening- according to computer command.
Probably your IAC motor or valve has a problem. A good cleaning often helps. Remove it and scrape off gently the deposits. Don't push the end piece, the pintle, back and forth, and don't spray cleaner up towards the little motor. Check the air passages where it mounts on the throttle body and clean as best you can. If it needed cleaning, take off the big boot and use a sensor safe cleaner, like throttle body cleaner, and old rags and old toothbrushes, and clean out the inside of the throttle body and the big butterfly valve, the throttle valve, inside. Note that when it is at rest, no gas pedal giving it gas, the throttle valve is almost completely closed. Those separate air passages in your idle control system, what the IAC motor controls, is the only way for the engine to get enough air to keep running. If they clog up, or the valve or motor doesn't work anymore, anyway the computer sees a wrong result from engine rpm sensors, and what it is commanding from the IAC motor, so it alerts you the problem is in the...in the idle cntrl system. Have at it, friend. It's either do it yourself or pay labor costs for a pro.

Check vacuum lines. Replace as needed. Clean the throttle body, inside of it. Use brake clean and a tooth brush. Clean the back side of the throttle plate and where it setts in the throttle. Clean the MAF sensor, just spray this down on both sides. Don't use a brush on this. You could break it. Once done cleaning, leave the MAF off. Start the car, it will take a second or two. Rev the engine up and spray brake clean into the throttle, not so much to kill the engine. Do this two or three times. Then put it back together.

I would have throttle body and mass air flo cleaned and see how she runs after that.If these items get dirty they can mess with computer and make engine run erratic.if still running bad have tps sensore checked.(throttle position sensor)these are noteted for idle jumping around.

I would start with checking the IAC ( Idle Air Control ) on the back of the throttle body. This provides air to the throttle body when the butterfly is closed ( idle ). Some times they build up gunk in there, and the valve cannot work correctly.

The IAC is on the back of the throttle body, you will need to remove the plastic throttle body cover to get to it.


There are 2; 8 mm ( 9 ? ) bolts holding this on to the throttel body, remove the bolts, and unplug the connector and the tube. Spray the IAC with throttle body cleaner that is MAFS ( Mass AirFlow Sensor ) safe a few times until the clear runs clean. Let dry and reinstall. Might need to be repalced, but worth checking on cleaning 1st.

My 1998 5.2 Dakota did the same thing... I removed the Idle Air Control valve and cleaned it with carb cleaner and my problem has been fixed (FOR FREE). At the same time I removed the Throttle Position Sensor and inspected it. I have read that running a very good fuel system cleaner in a tank of premium gas will help clean the carbon buildup on the sensors and throttle body. These two sensors are located on the Throttle Body and remove by unscrewing two Torx screws... the entire process took me less than 5 minutes. I know it is called an IDLE Air Control Valve (or solenoid) but my truck also did it while going down the road at certain speeds.

How to Clean the IAC Solenoid:
This is recommended at every Tune-Up to prevent excess carbon buildup on the IAC plunger. In some cases, you'll notice a slightly erratic idle quality. This is the first step in taking care of that problem. IAC = Intake Air Control (Solenoid).

• Remove the Air Hat from the Throttle Body
  
• Disconnect the sensor harness from the IAC Solenoid (Rear of Throttle Body)
  
• Remove the two Torx-25 Screws
  
• Remove the IAC Solenoid (Be careful not to lose the rubber O-Ring)
  
• Spray some Carb/TB Cleaner in the IAC port on the Throttle Body and let it sit
  
• Spray some Carb/TB Cleaner on the tip of the IAC Solenoid and wipe clean (Do NOT forcefully twist or push the plunger - You will damage the Solenoid. Wipe very gently.)
  
• Spray a little bit more Carb/TB Cleaner in the IAC port on the Throttle Body and wipe clean with a thin/lint-free rag
  
• Reinstall the IAC Solenoid (Make sure you don't lose the rubber gasket on the solenoid)
  
• Reinstall the sensor connector and airhat
  
• Start the engine and let idle for about 1 minute.