I've been having a problem with my car lately, idling very low. I adjusted the IAC valve by moving it clock ways but that doesn't do any good because when I put it from Park into Drive, the car TUGS vigorously and I don't like that. So I adjusted it just so when I put it into Drive it engages smoothly.

When I turned into a parking stall today, the car was idling just above 0. but it was like it was trying to breath hard and it finally died because the battery logo on the right came on. I started the car up and it started just fine. I don't think it's my alternator because I disconnected one of the battery terminal while the car was on and the car kept running.

What could the culprit be of my rough idle? Sometimes it will idle at 800 RPM when I start it up, but when I start driving it slowly idles lower and when I come to a stop at a traffic light, I'm always looking at my RPM's because it idles right above the 2nd line (almost to 0). Does anybody have any advice on what I should do? It's a 93 SC400 with about 162,000 miles on it.

 

so you are saying its happening because you adjusted the IAC valve? Or was it idling like that before?

 

It was idling like that before I ever touched the IAC. But I unscrewed it and adjusted it to see if it would make it better until I realized that it made it worse because when I put it from Drive to Park it would "tug" and I didn't like that hard engage, so I returned it back to normal so it engages smoothly.