Engine surging

[Kimmyis]

I rencently have developed a little engine problem. At idle the engine will drop down to almost 500 rpms then bounce back up to almost 1000 rpms. It will do this bounce back and forth for a while. Sometimes it will find that happy spot at around 750 rpms and idle normally and other times it will just keep dropping and surging till I put in gear and give it some gas.

Here are the things I know:
The car does it both when it is cold and warm.
Nothing else is out of the ordinary
We can sometimes induce the problem when the car is stopped at idle with the clutch out and we turn the steering wheel back and forth. The problem does not always happen when we are turning though
I believe that it has something to do with the car being wet. It seems to only happen when there is a lot of rain.

I went the mechanic a while back and they didn't experience the problem. Instead they charged be $300 to fix a problem I didn't know I had and could have fixed on my own. The possitive thing I learned is that there isn't an engine error on the computer from this surging. I am hesitant to take it back there.

If any one has any trouble shooting suggestions or answers I would be greatly appreciative!

[campaiar]

Clean your ICV.

Check for cracks in your intake plumbing.

[weezer]

Originally Posted by campaiar

Clean your ICV.

Check for cracks in your intake plumbing.

+1
Also, there is a very thin vacuum hose on the bottom of the Throttle Body that could be off and needs to be re-attached.
Check your spark plug wires, especially the connector boots; at idle try taking off each one of the plug connectors. When old, the boots could have a tear/fray that will arch the spark elsewhere, creating uneven idle......happened to me recently.
Good Luck.

[drrty byl]

Is the battery tightly connected? I've had this problem in the past when disconnecting my battery, but it always goes away after driving for a short while. I think it has something to do with the timing recalibrating?..