1993 mpv surges when cold and will not come off of high idle

Check the operations of the IACV and clean the throttle plate and also look for vacuum leak

Also go to this link for more information: https://www.2carpros.com/articles/engine-surges

I should mention that when I said cold I meant the ambient temperature. In warm weather the van operates normally. The surging and high idle occurs when the temperature falls below freezing. I have changed the temperature thermistor already and it has made no difference. No matter how long we let the van run, or how warm it gets(we drove 5 hours) it does not come off high idle. Any help you could give would be appreciated.