I'm not too sure about the reliability of the quad4, I've heard good and bad.
As for the Grand Prix, the 3.8L was rated one of the top 10 motors of the past 100 years by "Ward's autoworld".
I own a Grand Am myself (2001), and there are a few sites that may be able to help you out some.

www.grandamgt.com or www.gaownersclub.com would probably be your best bet

theres also: www.grandsontario.com although this one is based in Ontario, Canada, but they will be more than welcome to help you. I like this one because it more of a close knit thing because of the fewer people.

HTH,
Chris