90 ford van problems--random vibration in front end

Hi everyone again!
I have solved my other problems. It seems the low oil pressure was connected to the engine overheating (but not getting hot enough to blow any head gaskets or such). The radiator was so badly clogged up that it could not be rodded out. I replaced the pump, thermostat, and radiator and good as new. great oil pressure now, so on to next problem. . .

Here it is. . .the van will start to vibrate violently when applying brakes, harder I brake the worse the vibration. It also seems to be pulling to the right as well a bit. It doesn't alway vibrate when braking, though. There are varying degrees of the vibration. Sometimes its bad and sometimes it is non-existent. Very strange. The right brake seems to be clenching the rotor such that it the wheel doesn't rotate freely when jacked up. (maybe where my pulling to the right comes from?) Truly baffled, please make suggestions. I'll probably be taking it to a steering and suspension shop Monday, but I wanted to see if anyone had any suggestions for me before that. Thanks for any help! It is appreciated.