The only way to make it past World 7-3 alive is to carefully watch the enemies patterns as they move along the rails, and pass by them when they create a gap in their pattern.
Wait at Point 3 and watch for the row of enemies to begin tumbling down the circular rails. As soon as they pass by the second circular rail, jump across the mushroom pads to get past them.
It’s almost impossible to grab all the blue coins after hitting the P Switch at Point 4. So pick one row and stick to it!