1998 Buick Lesabre electrical issues

My car will just die from time to time. Whan it does there is no fire to the plugs and the windows will not work nor will the electric seats or the fuel pump. I had it put on a computer and it showed no fault codes. For some reason it looses all power to these areas. Then all of a sudden it will start and run for weeks before it does it again. Then when its running if you push certain buttons on the electric seat adjustments it will just kill the engine. Any ideas.