frickenbored

this problem has be driving me crazy from day one with this truck. Its a 1988 k5 blazer that has intermittent wipers. When i turn my wipers on they only have one speed and they are VERY VERY slow. sometimes when i go to turn them off they wont go off until i turn the switch backwards. I cant find a wiring diagram on these wipers but i have two connectors going into the wiper motor. the first connector is a three wire connector that plugs into the actual motor part (wire colors: purple, white, gray) the second connector is a two wire connector that plugs into the part where the gears are, i'm thinking this is for the speed settings. Has anyone had and solved this problem? I really don't want to throw a $50 wiper motor at it and have it do the exact same thing.