While you have the plenum off you might want to clean the inside with oven cleaner. they tend to gum up after 10 plus years. I used a tile brush taped to a drumstick oven cleaner, degreaser and carb cleaner. clean EGR tube too. Also replace any brittle vac lines, fuel return line and PCV / hose and grommet. Have fun. and be very nice to that knock sensor wire.