Yea mine is spring setup too man ima look at my motor mount make sure it's not completely gone and its causing my issue other than that I'm out of ideas

 

How old are your motor mounts?

 

112k miles that's not the issue though I've gone through 3 motors can't remember what brackets are on my truck now I went 4.8,4.8,6.0,turbo now I'm just trying to go 5.3 regular so I'm just going to buy the right headers for silverado sell what I got and call it a day