Scotty I have a 1999 Toyota 4Runner it idles up and down what causes that

Could be a number of things.. Same thing was happening with a friends Integra so we cleaned his Idle Air Control Valve, which was all clogged with debris and deposits, and it idled steady at about 650-700. Could also be Mass Air Flow Sensor needs to be cleaned or a bad Throttle Position Sensor.

I just did a quick Google search for "99 4 runner surging idle" found this page, check it out...

Hmm, won't let me post a link. Try copying and pasting the link into your browser