Is your brake light on, even when the E-brake is fully disengaged?
If it's not on, then my guess is something to do with your brake master solenoid. The solenoid is pretty complex; There are many things that could be going on.
But, you may not need the entire solenoid assembley replaced. Check the vacuum line going from the engine to the vacuum tree. It could be cracked, causing loss of the "power brake feel". Read through the haynes manual section on the master solenoid. It should give you a clue as to what is wrong.
Scott