WHAT CAUSES IDLE TO FLUCTUATE AND JERKING ON A 2007 FORD FOCUS 1.6SI HATCHBACK CAR. i HAVE CLEANED AND CHECKED THE INLET MANIFOLD, THROTTLE BODY, IDLE CONTROL VALVE BUT THE IDLE IS STILL THE SAME,

The 2007 Ford Explorer Sport Trac does not utilize the once-common idle air control (IAC) valve. Instead, an electronic throttle body is used. An electronic throttle body is a traditional butterfly throttle valve that has an electric motor attached to it. Instead of opening via a throttle cable, it is opened by the powertrain control module (PCM) when the accelerator pedal position (APP) sensor (which is the gas pedal) is pressed. The PCM also adjusted the throttle blade position in order to achieve proper idle speeds. Often times idle problems with this type of electronic throttle body are caused by carbon buildup around the throttle plate, in the bore of the throttle body. In fact, this is such a common problem with this particular vehicle that Ford released technical service bulletin (TSB) #12-7-4 to address the RPM fluctuation and hard start symptoms and advises to clean the throttle body. Alternatively, the throttle body can and may need to be replaced. You can read more about this issue here: https://www.yourmechanic.com/article/how-to-replace-a-throttle-body-due-to-carbon-build-up-on-most-vehicles-by-ty-thompson

There are a number of ideas here.

https://www.700r4transmissionhq.com/dodge-caliber-jerks-when-accelerating/

Lots more here. My idea is clean the Throttle Body and MAF.

https://www.google.com/search?q=2007+Dodge+Caliber+SXT+jerking+when+accelerating+slowly

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Perhaps check your fuel filter. A dirty filter will give an erratic idle yet run fine at higher idle/driving speeds.

It's on the throttle body where the intake manifold is this is round and has a plug facing up and 2 bolts where it attaches with a diamond shaped base

Is your engine management light on (mil) test it with obd scanner for code if light is on. If not you might have an air or a vacuum leak. This is very common! Open the hood and listen for a hissing sound when the engine is running. Unmetered air can enter the engine through a vacuum leak, a dirty airflow sensor that is not reading airflow accurately, an EGR valve is not closing and is leaking exhaust into the intake manifold, an EGR valve that is allowing too much flow. If it is hard to pinpoint take some brake cleaner or starting fluid around the intake manifold and vacuum lines and see if the engine stumbles or if the idle is affected. Be extremely careful when doing this!

Also, your throttle body may be carboned up and need to be cleaned! This can cause all sorts of idle and hesitation problems. This is caused by the throttle plate not seating properly. The First thing i would do is clean out the throttle body with some throttle plate and intake cleaner and a small brush.

Another common cause would be the Idle Air Control motor. This is very common on older cars. The IAC motor gets lazy and cant keep up with the fast idle changes. Also when the IAC motor is out, I rec to check the passages for carbon build up. If they are plugged they need to be cleaned out.

Possible Causes
Check for air leaks in the Air Induction system (e.g., in the intake manifold)
Check for air leaks in the PCV system and in its related hoses and/or valve
Idle air inlet passage or throttle bore is dirty or full of deposits
IAC valve has failed
Throttle plate, throttle shaft or linkage is damaged or sticking
TP sensor is out-of-range or "skewed" high

You do not state the age of the car or the type or the size of engine or whether it is petrol or diesel. On older E class models a fault in the over voltage protection relay would cause cars to be very jerky in idle. In general on petrol models I would start with the throttle body. Remove the air ducting between the air filter cleaner and the throttle. Make sure the interior of the throttle, the throttle plate and throttle area behind the throttle plate is really clean. Ensure that all all air ducting joints and vacuum lines to the inlet plenum are free of any leaks. On some engine variants the cam sensor oil seal over time can fail allowing oil to contaminate the electrical connection. Thoroughly cleaning the socket and replacing the 'o' ring usually fixes this. On diesels (3.2 CDi etc) the EGR feed pipe from the exhaust manifold around the back of the engine to the inlet manifold can become clogged with soot. Push a frayed bit of hand brake cable through it to clean it; clamping the cable in a drill chuck can make for a very effective flexible interior wire brush around pipe pipe corners etc. Any further information you can provide as per the opening statement would help in the diagnosis

on the inlet manifold,if your having a problem with the idle then remove the engine breather pipes that are just under the inlet manifold ,they are split and collapsed and the engine will not idle it will fluctuate like crazy

I HAD A FORD FOCUS AND THE PROBLEM WAS A MANIFOLD VACCUM LEAK AT THE HOSE THAT CONNECTS PCV VALVE TO INTAKE MANIFOLD. THIS HOSE CAN GET SATURATED WITH OIL AND COLLAPSE AND TEAR CAUSING A NO IDLE AND SHAKING CONDITION. IF THE CAR IS AN AUTOMATIC IT WILL HAVE TROUBLE SHIFTING BECAUSE OF INCORRECT RPM SIGNAL TO TRANS. CONTROL. ALL IS DUE TO VACCUM LEAK. ONE WAY TO FIND LEAK IS TO USE A SOLUTION OF DISH DETERGENT AND WATER IN A SPRAY BOTTLE AND SPRAY AREA AROUND AND BELOW THROTTLE BODY BELOW AIR CLEANER ASSY. ALSO LOOK FOR HOSE THAT ATTACHES AT MANIFOLD BELOW THROTTLE BODY AND BRANCHES OFF TO PCV VALVE SHOULD BE A "T" GOOD LUCK!!!!!!!!!

Have you tried the O2 sensors?