Yesterday I washed my engine. When I drove away my transmission started slipping. I checked vacuum lines and electrical connections before having it towed home. when I got home I fired it up to move into the shop. Forward and reverse both worked. I left it running while I opened the door and when I tried to move it in it was slipping in both forward and reverse. I turned it off then started it up again and for about a minute things operated normally. Then began slipping again. Any suggestions would be appreciated. Thanks