Rough acceleration and coolant runs out fast

What is your question?

I have a all wheel drive 91 ford aerostar and I don't know what could be wrong with it, when it gets to about 55 mph it starts to shake, not just the steering wheel, the whole van, and it runs through coolant like crazy we don't know if there is a leak or if there is a clog and there is alot of whiteish smoke coming out the exhaust but after it gets going that goes away a little, we just put new spark plugs in and spark plug wires, and it has 158,000 miles on it and it was overhauled at 110,000 miles, so were not sure on what it could be please help!