Have a leak water and antifreeze behind the intake manifold and firewall on my 1995 Toyato Runner what could be causeing this?

A leak of antifreeze and water from the freeze plugs or from a radiator hose could cause you to find the fluids behind the intake manifold and firewall on your 1995 Toyota Runner. You could begin by checking the hoses to see if all hoses are sealed and clamps are tight.