What games, homebrews or advise does anyone have on making running the game more of a Co-op experience.

I think the biggest obstacle to the cooperative experience is the GM wanting to control the game, by deciding what counts as the "real" stakes of the game.

So I think concepts like "the plot", "the adventure", "sidequest" - all terminology which prioritises the GM's vision of the game over the players' - is the enemy of the cooperative experience.

^^^
This. Very well said.