Recently my car had the CEL on and there was a lot of fluxuation in the idle when stopping, or going around corners. After changing it, the idle fluxuation when going around corners and such went away....but for some reason anytime I turn on the headlights, heat, or if the radiator fan kicks in the idles take a serious drop...and it's only getting worse. Before changing the O2 sensor doing any of those things would have a similar effect, but a much smaller scale.

Since I've owned the car I've already had to change the alternator once and recently changed the battery after leaving my lights on a couple of times. I was also thinking that it could be due to some sort of carbon build up (since i would exeprience the fluxuation when sitting at stop lights in the middle of the day) so I tried cleaning the throttle body, and the intake manifold....no luck.

Any ideas on what could be?

 

Is the CEL still ON?

Is the charge light ON?

You might want to clean the battery terminals and connectors, and also possibly charge the battery and have the alternator checked.

 

Have you tried cleaning the IACV?

 

Currently the CEL is not on anymore, as for the bettery terminals they're pretty clean, but i'll double check to make sure they're on nice and snug. As for checking the alternator, do most shops have equipement that can do it without completely removing from the car?

 

I know AutoZone can do it without taking it off the car and its FREE!

 

That's a good suggestion. Totally forgot about that. I'll give that a try too. I tried changing the PCV the other day, but that didn't help. I figured I would change it only because it was the original one that came with the car and I didn't know when and if the previous owner has already changed it.

 

In the U.S., AutoZone offers alternator checks free of charge, but I don't know if auto parts stores do the same in Canada.

 

Well I would give the IACV a good cleaning and if that dont help go have your alternator checked for free.