Thank you Sberci for the recommendation,! The DX hack (simonowen) worked for my stutter linked to my fanatec shifter. I run a rift s, Win 10 64, i4790, 1080, 32GB. Can run at high settings no stutter.
Tracked my stutter to my fanatec shifter. If I unplug it after game start it goes away. Soon as it is plugged back in it starts again. Doesn't matter which USB port I use.