I recently has my brakes get very hard. I thought it was the vaccum pump and I changed that, didn't fix the problem so I changed the brake booster and didn't fix the problem and has a new master cylinder. Changed the check valve and the vaccum sucks your finger onto the check valve so has plenty of vaccum. Any ideas

 

Hows the steering? Your booster runs off the PS pump. The suck pump only runs your heater controls. No fun on a van to do either pump. Usually if the PS pump is weak, when you press hard on the brake, the steering gets hard to turn also.