Idle fluctuates Nothing ,i read that air pockets in the cooling system can cause this

An idle meter can fluctuate for a variety of reasons, including a vacuum leak or a clogged fuel injector. It may be best to have a mechanic inspect your vehicle to diagnose the problem.

there is a bleed air plug in the upper radiator hose. be very careful because you can break the plug by trying to turn it full turns. it only needs to be turned about a quarter of a turn to half. you should also look into changing the pcv elbow. it gets a hole worn in it and causes the car to idle rough and even cut off in the drive thru line or traffic light. it is located towards the back of the engine and you may have to take off the intake cover and cam. i hope this helps.

When the truck is at operating temperature, touch both heater hoses. More than likely one is much cooler than the other. If so then alter truck cools off remove both hoses at water pump and blow thru one until it flows freely. If both hoses are the same temp (pretty warm/hot) then the blend door actuator has gone bad. Be sure to purge cooling system if heater hoses are removed, an air pocket will cause weak heating and and engine temp. fluctuations.

The radiator might have "air pockets". They cause erratic readings at the temperature gauge. Check the system to see if bleeder valves are provided. If they exist, just open the valves allowing air out of the system while filling with coolant until coolant drips from the bleeders. If bleeder valves are not provided, open radiator cap and fill with coolant. Start the engine for about 30 seconds, check coolant level and fill to level if necesary.

typically this vehicle utilizes a map sensor or what is known as a speed density system the vac operated devices that draw enough to cause it to stall are the 1. brake booster 2. pcv system 3.any of the rest of them would cause a fluctuating idle but the pcm could compensate we know the idle air control system is working because the idle surges so i would first remove the fresh air hose from the throttlebody the dry dirt around the butterfly valve accumulates chocking the airflow off and causes a low idle this is known as coking and is very common also check for EGR codes if egr solenoids 1 or 1,2 or 2 or 3 are stuck open this will cause a low unstable idle or stall and the tps voltage at idle should be checked 3 wires 1 wire should be ground 0.v 2nd wire should have a 5v reference and third wire is what is known as signal return it should read at idle around .5v to 1.v if it is not in this range then it will cause the same symptoms

You need to have your system pressure tested. There is obviously a leak which is causing an air pocket. The pocket causes the temperature fluctuations. This could be as simple as a pinhole leak that caused the pocket over time or as complex as a head gasket allowing pressure to build up in the coolant system can cause fluent to leak out the overflow.

I had a similar problem. Replaced head gasket, but low coolant light stayed on. My problem was air in the system. A flush and fill kit may work, however, I had a local shop do a "flush and fill" and the problem remained. What I did... With vehicle running, and radiator cap off, bring engine to operating temperature. Increase rpms slightly above idle until coolant can be seen moving in radiator (thermostat open). Add small amounts of coolant, keeping the radiator level just below overflow hole in cap area. In my case, after about 15 minutes at slightly above idle rpms, a large pocket of air escaped. I topped off radiator, installed cap, and let engine cool. Problem has not returned in last six months. *Note coolant is VERY HOT, and if rpms fluctuate, coolant will expel quickly from radiator. Also, when the air pocket escaped, coolant also sprays out. Use caution to avoid being burned.

have you had any cooling system work done? possibly an air pocket in the system

One guess is there is air in the cooling system. The air pockets will cause temporary overheating (fluctuating guage).

It sounds like a bad head gasket is creating these air pockets.

Check for a vaccum leak at the intake. Frankster016