What would be the prob if my van sounds like a lawn mower?Among other problems

I have a 1991 plymouth voyager, it came from up north so the who;e under side is rusted, I have replaced 3 brakes and a few lines. When I start it up it sounds like a lawnmower and get louder when im driving like when I give it some gas, it stalls when I shift it to reverse if I dont hit the gas pedal right away, its has around 150000 miles but most likely more cause my spedometer does not work, only when it wants to, and the whole van shakes when im stopped or when I idle at a light. Please help need answers to all these issues