I’m not exactly sure what

I’m not exactly sure what you are doing but perhaps this could help. I think the problem may be in your export of the clip because premiere shouldn’t change a file upon import if it is a "microsoft DV AVI"

In the export movie settings under the video section, make sure the recompress box is NOT checked.

Also, in the keyframe and rendering section, make sure you are using maximum bit depth.

Best Regards