Touring Suspension ?
 

How can I tell if a 2002 Merc grand marquis gs has touring suspesion? Also,anyone know of an option decoder?

I am sorry to say i dont have any idea on this.Its better that you consult some one else.

you could try a vin decoder and see if that's listed as one of the installed options.

just google mercury vin decoder and type in your vin. usually you can leave out the last few digits because they're your car's serial number and it 'might' be a security risk... somehow.