i have an '06 pontiac grand prix that the wipers mostly only work in high speed....then out of the blue all speeds will work for a while(minutes, hour or two) only the high speed works perfectly all the time....Is it the switch? a relay? a short somewhere? any ideas?

This sounds like your multifunction switch is slowly giving up on life... For your reference, the inner workings of a multifunction wiper switch is nothing but a dumb array or variable resistance. After a few years, the contacts inside the switch could wear, corrode or break. You could easily take apart your steering column cover, disconnect the switch and take it apart to expose the fingers/contacts. With a multi meter (Ohm meter) measure the resistance of the switch at each of the position. Take a look at this sample wiring diagram (top center shows the wiper switch) http://ww2.justanswer.com/uploads/s420/2010-11- 15_183241_92_continental_wiper_wiring_diagram.jpg