This probably doesn't have anything to do with your noise, but are you sure that you have the proper subframe mounts and they are installed on the proper sides? The post-85 126s have a different mount than the pre-86s and they are side-specific. If you put on a set of pre-86 mounts, they will not be right for your car or if you put on a set of post-85 mounts and didn't put them on the proper sides, they won't be right . . .

Richard Easley
Waco, Texas