My taurus is making a loud hissing noise only when I accelerate. as soon as I let my foot off the gas it goes away.

raise the hood,start the car,then move the throttle cable with your hand ,and see if noise is coming from under hood area.maybe vaccum hose not connected or split.check around everywhere,pcv valve,etc.

You may have a bad vacuum hose or the air filter housing isnt secured right. Also make sure the dpfe sensor hoses arent disconnect or melted by the hot gases coming through. If the dpfe hoses are melted or the sensor itself if melted or damaged tou may want to replace your converter