Hello,
As long I am playing i noticed that when the npcs are walking, their feet seem to hide in ground many times. I mean that when for example they climb a hill, their feet will dissapear in ground and re-appear etc.
I was thinking if this is a problem with the models of the game (with ground for example) or it has to do with mis-placed path grid (path grid that lies in ground etc). If it is caused from path grid i should correct this somehow...
Till now I havent found any way to move up or down a path marker as It can be done with models.
Can you give me your lights?

I don't think that this a pathgrid
I don't think that this a pathgrid problem. Oblivion simply doesn't adjust foot position to ground slopes. There is a mod that claims to correct this, but I've never tried it:
http://oblivion.nexusmods.com/mods/42222
Edit: Ohh, I just noticed that this mod only corrects foot positions of the player