2004 Honda accord, 4 cyl idle is going from a normal idle to 2500 rpm up and down. Anyone had this problem, after a lot of research the best diagnostic is the IACV valve.
IAC is the most likely cause - unplug the electrical connector to it and see what happens. The idle should be more stable (the speed may be way off, but it should stop hunting). Vacuum leak is also possible...spray carb cleaner around the intake and see if the idle changes when it is sucked in someplace.
