The idle is low and flexuates up and down and the check engine light came on.

Sounds like a low fuel pressure issue or a stuck open egr valve/air leak.

I'm sure your check engine light is on try....
https://www.autozone.com/landing/page.jsp?name=top-five-reasons-check-engine-light

Check that the idle speed is not too low in drive . Should be around 900 rpm in neutral and the idle speed is adjuste in drive to no less than 750 rpm. IT takes rpm for the alternator to charge the battery so if you have 11 volts then the car is runnung off the battery and not the alternator. It needs 13.5 volts to charge a battery and most regultors are set at 14 vvolt to 15.5 volts. If the vehicle is runnung from the battery as I stated then items like blinkers and stop light operation will show as fluctuations on the gauge. Have the system check . Make sure the drive belt to the aklternator is correctly adjusted as a slipping belt will also cause a problem.

the idle being low most likely wouldnt set off the light, it has to be whatever is making the engine idle low, such as vacuum leaks or the idle adjuster

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Check the fuel psi. and for vacuum leaks with a can of carb cleaner. How you check is run engine at idle and spray all vacuum lines and intake -if idle goes up or down there is your leak.

Check the basics first.

Is the check engine light on ??

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There is a coolant temperature sensor on the top engine block to measure the temperature. Either the connector is loosen or the temp sensor is bad. This sensor is bad will cause the gauge reading fluctuated. Locate the temp sensor and replace it to take care of the problem.

CHECK GAGES light (1) indicates a potential engine failure(low oil pressure, low coolant, coolant overheating) has occurred.
· Check gages and shut down engine. Gages should read as follows: Oil pressure 5 to 10 psi (34 to 69 kPa) at idle; Water Temp gage below 230 degrees (110 C).
· Check engine oil level (Para 2-11) if OIL PRESS gage indicates low reading. Check coolant level (Para 2-11) if Water Temp gage indicates high reading. Notify Unit Maintenance if levels are low.

If CHECK ENGINE light (2) is on, check engine oil pressure gage (3) and water temperature gage (4). If both indicate normal, proceed with mission and then notify Unit Maintenance. If either one does not indicate normal, stop engine immediately and notify Unit Maintenance

Idle sensor is bad. Find a autozone for check engine light they will connect to computer for free, and tell u what codes come up they can give u a printout also.

Check engine for vacuum leaks at all hoses, hose connections, intake gasket etc. I have also seen retarded engine timing produce low vacuum. If no leaks, check anything in control system that controls timing...however, I believe you will find a leak before you need to go there. Also check Idle control valve and egr valve for malfunction or blockages.

Here is the most common cause of surges and stalls and low idle rough idle, it is the idle speed control air-bypass valve and throttle valve (IAC for short), they get full of gunk over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake.