One of my sites has been regularly appearing and then disappearing from the SERPs for the past few months now. It goes from #3-5 for a certain key phrase to nowhere in the top 100 on a daily basis. It may disappear for several days, then reappear at the top of the results for a few hours...then it's gone again. I haven't been making any changes to the site during this time. All other results for this key phrase seem to be holding steady....only my site is doing this. Also, my rankings for all other relevant search phrases are holding steady. Any ideas?
Thanks