Well well looks like someone's been reading up on ancient greek democracy
I don't like it. The tests assume smarter is better, which is rarely the case. Using test also guaranties that the assembly would not be representative of the populus (who represents the morons?). In fact the result of this solution would not be 'democracy' in any form.
On a more practical note, and this applies to any arguments for term limits as well, you lose an enormous amount of institutional knowledge. Being a politician is not just having opinions - there's (or there should be) a lot of pure skill and hard work involved as well.
I expect the result would be a bunch of puppets in congress being manipulated by skilled lobbyists, who know the game a hell of a lot better then the congressmen do.
The governmental bureacracy would also be so much more skilled that the congressmen who'd be completely at their mercy, and the bureacracy would become the real power.