If cold high idle is normal, then check temp sensor contacts for corrosion. Also check the hose from the idle control valve to the bottom of the airflow meter plenum - it might have been knocked off. Also, don't forget to check contacts on the Bosch computer boxes behind the access panel, if high-pressure water entered there.

A general rule of attack, though, is not to adjust something that could not possibly have caused the problem - such as the mechanical mixture control. Now, in addition, you have a screwed-up mixture adjustment that will only add to the complexity of solving the problem.

Steve

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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7