So here's the deal...

My car has been idling really low (510-550rpms) since last december. I originally thought I just got some bad gas, but it's obviously last longer than a tank of gas.
It generally idles like this 90% of the time, and only after it's warmed up. After it's warm, if I kill and and then start it back up, like if I go into the grocery or something, the car tries to die then catches itself and settles at a "normal" idle.


The other problem:
My car had to sit for almost two weeks (rear window vandalized, had to save moeny to fix). I fired it up once, after about 9 days or so, just to make sure the battery wasn't dead or anything - ran it for about a minute and it was fine. A couple days later, I fired it up and take it to be fixed, and all hell broke loose. It SOUNDED like the crank was rattling and it wasn't firing on all cylinders, and I could hear the lifters ticking louder than usual. It had oil, albeit a bit low, but plenty. Tried to give it some gas and it sputtered and tried to die.
2 days later, fired right up and ran fine. WHAT THE HELL!?!?!

Oh, somebody told me this could be a sign of my H2O pump going out... that sounds ridiculous to me, but what I don't know never ceases to amaze me .

 

I have the same problem right now. i want to find out what it is too..

 

I just called a local shop and he said it SOUNDS like it's the idle air control valve. Said it probably just needs cleaning, which is @ $60, but a new unit costs somewhere around $200. Not sure if that's the problem or not, but I'll find out this week.

 

IAC's and MAF's go hand in hand. Sounds like your MAF sensor may be going bad as well. Someone else on the forum is having a similar issue. I told him it may be his MAF as well.