Okay I made a mod and place a NPC across the river from the start sewer. I have a save that is in the river when I go to him he falls from the sky and dies. But if I come out of the sewer he is where he is supposed to be. Do I need to do something to fix this or will he go where hes supposed to as long as your not near him when the game starts?

Go back into the editor and move him to ground level. Hold the Z key while moving him with the mouse to move him vertically.

He'll appear wherever you place him, so if you place him fifty feet in the air, that's where he'll appear.

....thank you lol

Don't forget to use the key "f", a much quicker way to make the object fall.

And when you do that, make sure he's on the ground. The "F" key makes the placed object fall until it contacts something else, but it could be the tip of a tree, or a building. When the NPC's AI kicks in, he may then walk off it. That won't usually kill him, but it could cause other problems if he knocks things out of place during the fall.

I've had this happen, too.
After you've placed a NPC/Creature where you want them, turn on
path grid editing in the CS, and you can see if it's on the path grid,
under, over, off it, or on it correctly.
Remember, with path grid on, you can only move the path grid points
around, DO NOT try to adjust the any object around, with path gird on.