I've been having this drifting issue with certain larger models, I recently ran into the same issue with a small and simple one, so I figured it's a simpler question to disect:
If I print one copy of the bushing it prints out straight.
If I print two side by side, they drift in the X-Y plane, see pictures. Using simplify3d. It's thin and printed solid by setting the outer shells to 10 to avoid any infill.
Your thoughts would be greatly appreciated.