SERP change every few days in a certain pattern

[Benj25]

Every 2-3 days, presumably each time we are crawled we go from 2nd for a chosen keyword - to 4th for a chosen keyword. Then 2-3 days later - back to 2nd.

It's always the same two listings that come above us, and go back underneath - why would this be?

[EGOL]

You might be in a close battle!  I would improve optimization if possible and try to get more links!

[Benj25]

We've done everything we can with regard to on page optimization. More links it must be.

[Dan-Petrovic]

Back in the day I would say it's two datacentres being queried. Then again I've seen algorithm testing do the same thing. Latest observation was the PageRank stuffup by Google and it was interesting to see results jump up and down as they were recalculating it. Not a factor guys huh! Think twice