Where is the idler pully on a 1997 cavalier?

Get a standard 3/8" socket wrench, just the socket wrench, you don't need any sockets. Look on the idler pulley bracket for a square hole in the bracket. Place the socket driver in the square hole. You can now easily move the idler pulley to relieve the belt tension and remove the belt. I found that my 3/8" ratcheting socket wrench was too thick in profile to fit in the rather narrow space on my 1998 Cavalier. So, I bought and used a 3/8" breaker bar which happened to have a thinner profile and it fit and worked very well. There is also a thin profile tool made especially for serpentine belts with little clearance at the tensioner.