2001 Chrysler Town And Country brakes problems

My wife told me that she had a close call; almost hit the car in front of her some time ago because the van would not come to a complete stop fast enough. Last night on the highway, I pressed hard on the brake pedal. The car slowed down but would not come to a complete stop, resulted in bumping into the car in the front. Both the passenger and I thought the van should have stopped in time to avoid such an accident. Although I was pressing hard on the pedal, I could not feel any pumping of ABS.

Dt*: the contact stated while traveling at various speeds and depressing the brake pedal, it had to be pumped to get the vehicle to stop. The vehicle was driven to the contact's residence, and then towed to the dealership. The master cylinder was replaced. Two and a half years later the problem returned and the master cylinder was replaced a second time. Updated 1/31/2007 - three days after the master cylinder was repaired , the problem recurred. The problem was found to be some type of faulty control unit.