Help with braking problems on a 98 Acura Integra

OK so here it goes. I was driving along and all of a sudden my car acts like it has brakes on. When I start to drive it drives normal until I start pressing the brake. As far as I can tell the brake does not act really stiff or soft. As I drive and keep pressing the brake the brake pedal does stiffen slightly. When I take my foot of the gas the car acts like it is dragging. Then the car drives hard and you wonder if you are going to make it home. When I stop all four brakes are hot and making a slight popping sound as to cool down. The wheels are to hot to touch. I took it to a mechanic and he disconnected the ABS system. This only worked for about 20 miles of driving until the car is doing the same thing. Talked to dealer and they say possible proportion valve, mechanic is thinking master cylinder. Today he and I took if for a drive. When we came back he took a plastic piece off and when he did air came out. He was blowing on it. When talking to him or dealer they have never heard of all four brakes getting hot. Any thoughts?