96 monte carlo idle fluctuates when standing still. Also lights go dim when idle drops. changed both O2 sensors, battery, tensioner belt, and altenator. Mechanic thinks its the choke sensor but knows thats not what the name of the part is called anymore. please help

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Question moved to model category.

That sounds like a flat battery, you left the lights on or something.

Put the headlights on and turn the key to start. If the lights dim to a yellow glow worm, the battery is flat.

replace the o2 sensor(s)

go to your local auto parts store and they should have a scanner but it sounds like eather the Throttle Position Sensor or one of the O2 (oxygen Sensors)

It is the one that is before the catalytic converter

you possibly have worn contact brushes in altrenator so when motor revs drop the alternator can keep up with power demand also check battery & all batt cables check alternator drive belt

posable voltage regulator

it does sound like a bad crank sensor

Hi you need a fuel level sensor

I can surely help bet let me ask exactly what codes are you getting?if you have multiple codes maybe clear them and run it untill you start getting current codes,I have lots of info for you but get me the current codes Relax...we will get it fixed but keep in mind it wouldnt hurt to put a noid light on the injectors 1,3,5 because you may have a quad driver problem in the pcm.let me know have a good day DB

if you remove the battery and charge it than reinstall (make shore all lighting and non essentals are off) and if the car runs for awhile then the problem most likely is with the alternator