I had this problem when my 7900 was brand new. The Decision 1 tech came out twice and couldn't figure it out so we just turned off the auto nozzle check/clean feature off. It still ran very occasional spontaneous checks/cleanings for me, but nothing like every 2-3 pages. Also, I couldn't replicate as it was infrequent-- with the exception of the cleaning that happens when switching from pk to mk or vice versa (it runs a cleaning on the switch, but inevitably runs another cleaning later when you go to print).
There were a couple of quirky things like that that I never solved which the tech chalked up to having one of the earlier 7900s when they just came out.