Its not hard to check if the DISA valve is broken. Just unscrew the 2 torx screws and unplug the connector at the top of the unit. Pull the unit out from the intake manifold and look at the flap. Here's what a broken DISA valve usually looks like.
Flap Loose but still in place
Pieces that broke off which hold the flap in place and rotates the flap open and closed.
Close up of broken part.