boosted99 
I have owned my 1999 GTP since August of 2011 and here is my journey. On the way home from picking it up the ACC stopped working after reading the forums I determined that my car has the Auto Climate control and they are a real pita once you start having trouble. I have replaced the main unit that you use to control the a/c this did not fix my problem, next I ordered a climate control module (btw if you have the Auto Climate Control you will not have the resistor you have a module) Here is what it looks like I got it from ebay: Grand Prix Regal Blower Motor Control Module 52479971 | eBay. When I got the part I could not get the other unit off due to the fact that a contortionist is required to get to the bolts that mount the damn thing. So I did the next best thing I simply unplugged the mounted one and plug the new on in and my a/c worked, however when I unplugged the grey and black connector I noticed one side of it was black (looked like it had got hot) I knew this may cause trouble later down the line.
Anyway 2 months later and after consecutive 100 degree days in Texas the a/c stopped working again. I unhooked the connector to the module and plugged it back in and it started working again, this lasted for about a week. I can wiggle the connector and get it to work but I decided it was time to scour the internet and find a connector to fix the issue once and for all. Here is where I found a new connector and what it looks like: https://www.carpartsdiscount.com/aut...ml?3593=318621. In between these problems my car started running very rough and a diagnostic said #3 cylinder miss fire, long story short after replacing the plug, plugwire, #3 injector and the coil pack (about $100 for all), I read that the injector clips go bad so I order one from here http://www.rockauto.com/catalog/x,ca...Bfor%2BPONTIAC and my last problem has been solved.
I have also just finished doing a tune up and everyone who says the back plugs are hard to get to and you must rock the motor forward are crazy I am a big guy and I did them in the same amount of time it took to do the front plugs and did not have to rock the motor. I hope this helps some of you and if you have any questions shot them to my pm.. Thanks
