What happened in the 1990 election? What about all the pre- election "throw the bums (incumbents) out" sentiment?
The fact of the matter is that few incumbents were unseated, because they typically spend 5 to 10 times the money on slick TV advertising, than do their challengers. Where do they get all that money? From PACs - Political Action Committees, funded heavily by corporations and other special interest groups.
The PAC campaign system must be abolished, and spending limits put on political campaigns. In addition, terms of office need to be limited - some states have passed laws requiring this. ***