When i turn on my car its really shaky and when i put on reverse or drive it turns off. HELP!!?

my car its a 4 cyl, dodge, w/2.2 engine. the car starts good, once its on it shakes, i can have it on all day and its ok, but when i put the gear it turns off in a sec, no matter if its reverse or drive, if i put it on gear and accelerate a little it will stay on.