I have been working on this for 2 days straight now.
I finally found a solution... almost.
I use this code:
<?php wp_nav_menu( array( 'container_class' => 'menu-header', 'theme_location' => 'primary', 'menu' => get_post_meta( $post->ID, 'MenuName', true) ) );?>
And create a new custom field called MenuName and give it a value matching the name of the menu you want that page to use.
But it only will only show one menu?
How can I make it show 2 menues on the pages i would like to have 2 menus?