99 SR5 idle problem

At times my engine's idle RPM fluctuates from 400-800. It only happens once or twice a month and my 4Runner has never stalled b/c of it, but I'd like to get it taken care of before I get stuck.

I'm just wondering if anybody has this problem or knows of a possible cause

Thanks.

Hey my 95 4runner has had similar problems. I actually just took it into the shop because whenever I would come to a stop, the idling would drop to about 200 RPM, and would sometimes stall. Long story short, I get the car back doing the same thing and they told me it would need a new throttle body. Turns out that a few of the vacume hoses were actually put in the wrong spots. Put them back in the right places, and it doesn't do it anymore. It does fluctuate a little bit, but not sure about that...maybe the timing is off?