sheebaracer

i just bought a 95 4runner and am trying to figure out the window situation. when i first went to look at the 4runner i tried all the windows and all of them worked except the 2 back seat windows. i tried with drivers switch and other switches and still nothing. then on the test drive i decided to try again and the drivers back window was working all the sudden but still nothing with the passenger side back. since i got home both of them stopped again. i have a few extra switches and motors laying around. i have tested all motors and switches and they are good.. could it be a regulator? both of my front windows work fine still.. any suggestions would be great.