I would *gently* hose it down, very low pressure with some mild soap. Clean the chain with degreaser, make sure its dry and clean, and relube it *using a quality bicycle lubricant* (ie, not WD40 or motoroil). If the shifting is sloppy maybe give the adjuster barrel on the rear derailleur a 1/4-1/2 turn and see where that leaves you. Check to see if the headset is loose by applying the front brake and rocking the bike backwards and forwards a bit with the wheel locked... if the headset is loose you will probably notice that it feels kind of sloppy or is a bit noisy when you do this. Check the true of the wheels, check to see the brakes are in far enough.... should be pretty good to go after this.