The first thing that I would look into is the Idle Air Control Valve, IACV, which is sometimes also referred to a the engine Load Sensor, ELS.
This is an electro-mechanical device which idles up the engine when loads such as; power steering, A/C and other accessories or situations call for it.
Electric items are tough as they fail intermitantly.
Other suspects are vacuum leaks and emissions items such as the Exhaust Gas Return Valve, EGR.
Listen for a vacuum leak while the motor is running under the hood. Also, Try running a can or 2 of BG44K. It will work wonders. Make sure to change the oil afterwards as it works so well, it makes the oil really dirty.
Pull the plugs and tell me what thney look like and listen for a vacuum leak and get back to me and we will go from there.
It can adversely affect the performance of the engine.
It is tough to diagnose problems such as these because electric/mechanical control modules feed from sensors all over the engine and accessories which makes it hard to tell if a sensor is bad, the control unit is bad, an IACV is a control unit that sometimes has integrated sensors, or if the is a problem with the Vehicle Main Computer.
Friday, January 7th, 2011 AT 5:03 PM