The serpentine belt tensioner pulley and the 3" supercharger idler
pulley didn't spin very easily as they should.
Rather than wait for them to seize up and destroy another belt, I
replaced them. Each pulley cost about $20.
I took pictures of the process and created a quick guide.
Here's the guide -
http://www.paulstravelpictures.com/GM-Pontiac-Grand-Prix-Idler-and-Tensioner-Pulley-Replacement-Guide/index.html
I hope someone finds it to be useful.
Cheers,
Paul Michaels
Ft. Lauderdale, FL