Is your 'POWER' light blinking when you start the car? If that light blinks on startup, then you have an electrical problem with the transmision which will cause problems for you.
How did the transmission behave
before you adjusted the brake band? If the adjustment you made changed things at all, even for the worse, please detail that change.
I think it's likely that you have worn clutches in your transmission, though. Start saving because you're going to need a rebuild.
