Easy way to tell if the coupler is bad is to take the supercharger belt off and see if there is any play in the pulley (turn it back and forth by hand)

Does it just make noise and vibration, or can you feel the car bucking any? (like your losing power on and off)

There's a good chance it is driveline related, or could even be a misfire.(Though usually if it misfires a bunch the SES light will flash on and off for a few seconds)