Idle Surge on 2003 Honda Odyssey

My engine surges at idle to about 1100 rpm. It does not always do it. My mechanic has checked everything out and can find no problems. He confirmed that the O2 sensors are good and that the IAC valve is good. There are no fault codes set. It does not matter if the engine is hot or cold when it happens. Any thoughts?

2 answers
Problem solved. It was the power steering pressure switch. It had a faulty electrical connection.
Idle goes up and down around 1100 RPM?