This stage is very difficult. Start off by going up the elevator and right. The platform to the right of the eyeball will disappear when you step on it, so you have to jump from this spot. It's a little tricky, but you can manage it. Once you make it to the other side, destroy the flashing brick and use the elevator. Climb the ascending platforms and enter the door at the top. Keep going to the right and onto the elevator. Jump over the two holes to the left and the fall onto the platform above the first elevator and it will disappear. Shoot the two flashing bricks on the second elevator, fall off the right edge.
You'll be back at the second set of ascending platforms. Head back to the top and then left again to the two elevators. This time jump over the hole above the first elevator and fall onto the platform above the second elevator. The platform will disappear and you'll be able to use the elevator. Take it to the top, walk to the left, jump over the two holes, and then the ball. This is a dead end, but you'll see a flashing brick far to the left that's important. Hit it, jump back over the ball, and then fall into the hole. You'll land on an elevator. Take it up. Ignore the door to the right and jump to the left where the ball is bouncing. Duck under the ball, fall to the left and take the elevator there up.
Walk off the right side when they ball isn't around, and wait beside the elevator. When it goes back down, center yourself on the platform, and then jump across. Continue to the left but watch out for the ball when you're going up the ascending platforms ahead. There will be two more balls, this time going vertically ahead. Slip under them and use the elevator ahead. Enter the door at the top. Climb the ascending platforms and enter the door at top. Duck under the first ball, and then wait for the other ball you'll see to pass by, and then climb until you see the second to last door. Enter it. When you reappear, wait for the ball you saw earlier to pass by again, and then make a break for the elevator.
You don't have much time, so you have to be very quick. Occasionally, a ball from the far left will be bouncing toward you when you're coming up the elevator. Start tapping 
and you should hopefully kill it before it knocks you off. You're almost done at this point. Walk to the left and carefully make your way under the two balls floating around. Wait for them to line up so that you can just walk straight to the other side. You can also just stand under the first one, and wait until the second one goes back up and then walk to the other side. Don't wait here two long or one of those annoying brown molecules will appear. Once you're through, walk to the left, use the elevator and enter the door to finish the stage.