Car problem


I have a 1990 mustang automatic and i just changed the spark plugs, wireset for the plugs, distributor cap, rotor, but it still shakes when the car is in gear…it idles fine but when i put it on gear either reverse or drive while pressing the brake it starts to shake wildly and almost wants to stall out…sometimes it does stall out…i really have no idea what it could be and would appreciate the help…


Check for a vacuum leak.