Pygame falling shape and keyboard input

I want a shape in pygame to fall down slowly. The user should be able to move the shape with the arrow keys. My code is given below:

while Running:
Keys=pygame.key.get_pressed()
if event.type == pygame.QUIT:
Quit()
elif event.type == pygame.KEYDOWN:
if event.key ==pygame.K_LEFT:
x=x-1
y=y+1
pygame.time.wait(3000)


However, it doesn't always take in the keyboard input if the shape is falling. e.g I will have to press the left arrow key 5 or 6 times for the shape to move. Any idea how I can sort this out?

update: I think the error is in the following code, but if I don't have it then the shape falls too quickly.

    pygame.time.wait(3000)


Also note, that you don't have to use integers here. You can just as well decrement x by 0.1 for an example. This would end up meaning that the block moves one pixel in ten frames.