1994 cadillac eldorado.will not idle.stalls out when stopping.when in part idles up and down

Does the vehicle start after sitting over night or do you need to jump start it . Is the charge light on ( batt. symbol ) at any time ? Serpentine belt good , tensioner good ? Battery cable connections good an tight and no corrosion ? Battery also good ? That is normal for battery voltage to jump up to 14 volts after starting , alternator is replenishing the battery after starting ,that draws down the battery . Going down to 11 or 12 volts when stopping and almost stalling isn't a charging system problem . You have a idle problem , IAC - idle air control valve or dirty air passage , a vacuum leak . Giving it gas and it going up to 13+ the alternator is working . Your best bet take it to a qualified repair shop and have it check .

Sounds like the front of the radiator or A/C condenser is clogged up...take a water hose and try to clean any debre from the front, so air can pass freely...

replace the idle speed control motor

a vacuum leak or a failing idle air control valve will cause this. i would first look for a vacuum leak by looking all the vacuum hoses over for crack and broken lines. very common.

sound like leaking head gasket.have the radiator shop check and pressurise coolant system.check for leaking head gasket and intake gasket.

First impression is a MAP sensor. If you take the car to a service station or an auto parts store that features free diagnostic tests, I'm sure the MAP sensor fault will appear. Other cause could be the TPS which controls the idle at cold,warm, and AC operation settings. It's possible that you're stalling due to insufficient idle speed setting on the TPS.

I am not sure if this will help you but PO27 is listed as "Open Throttle Signal Switch" which could mean that your throttle position sensor needs replacing. Although with Cadillacs, it could mean anything. I hope this helps...

o2 will not make your car do that you have other issues check for secondary ignition miss or primary ignition miss sounds like you are dropping a cylinder dumping raw fuel to contaminate 02 sensor find the real problem to fix your light

sounds like the iac motor or the idle air control

I have a 1994 Cadillac Eldorado and every time i start it the car has rough Idle and the Idle fluctuate's. I also can feel it in the gas pedal when the car is doing this I tried replacing the throttle body sensor but it still does it I also was told it was the Idle error sensor. So instead of spending the unecessary money again I thought I would go online and see if anyone could help me with this problem.