I didn't use very much water, however the mister had a bit of a drip at the bottom of the spray pattern, so some of the water didn't make it all the way through. Probably best to use a finer spraying mister, but I think you'd still cause the idle to dip because you're messing with the MAF's ability to determine airflow.
I think my ISV is flaky anyhow, so I'm not too concerned. I shot a small amount of carb cleaner into my ISV and on the MAF wire and all is running well again. Speaking of cleaning the ISV, has anyone used this LPS stuff before?...
http://www.jageng.com/LPS.htm