This was on my wife's SDV6 RRS.

Following on from my DPF/restricted performance problem, I happened upon a video showing how the butterfly in the throttle body could get stuck in the closed position.

I wondered why they get stuck, carbon build up perhaps! Anyway, I took the body off and gave it a good clean with carb cleaner and got rid of as much built up carbon as I could.
I then set about trying to solve the sticking butterfly problem.

To cut a long story short, I eventually placed a flat blade screwdriver against the inside of the throttle body and the edge of the open butterfly, by the butterfly shaft, then gave it a very gentle twist. My idea being it might just move the butterfly along the shaft a tiny amount. To my surprise, it worked and is now back to normal.

The photo shows where I placed the screwdriver.

I hope this helps some of you. It's certainly cheaper than a replacement.

Click image to enlarge