2005 cts

My 05 cts 3.6 is shaking very badly while I idle. I also have a problem accelerating and its shakes and stutter during acceleration. I also hear a very loud knocking noise coming from the rear like someone is literally smacking something with a hammer.... please help

Replaced the spark plugs, cleaned the Throttle Body, and checked the Air filter. It vibrates at idle and worse when the Ac is on. When driving it’s bad at 30-50mph and smooths out after that. Motor and Trans mounts are solid. Curious if there’s something I’ve failed to check. Any and all info on...

Hey all, hoping this reaches out to anyone. I've noticed that there are absolutely no aftermarket parts for any 03 - 07 CTS with a 3.6L and I'm looking to get creative with my own and hopefully share with you all the knowledge I learn as a part of this project, seeing as how no one runs into any...