2002 grand prix gt - radio , power locks , power seats all went out @ once?

SOURCE: 2002 Pontiag Grand Prix GT 3.8 Runing rough and stalling at stops

sound like vacuum leak or fuel pump problems.scan it to see if egr valve sticking open.

SOURCE: horn

check and/or replace your relay (fuse console in engine compartment)

SOURCE: THE ROMOTE STARTER WONT WORK ON MY GRAND PRIX I

the reciever might be blocked by something,dirt,a loose wire,etc.or a wire might have come loose to the starter from the remote.

SOURCE: 2003 Grand Prix GT - power windows

NEED TO CHECK ,MAIN POWER SOURCE ON DRIVERS DOOR OR MAIN CONTROL

SOURCE: Car Heater Not Working - Blowing Cold Air

also check to see if tube that runs your climate door is not pinched or broken. the vaccum tube that runs the climate door is behind and under the battery. i had same problem a year ago and the tube was partially cut. i fixed it by cuttinga piece of aquarium tubing and spliced it back together. one other thing.....check to see if your radiator over flow cap is tight. your cap maybe bad and or cracked this would also cause the problem.