My wife had a starting stumble. I looked on here & found advice about depressing the clutch etc. We finally found the problem. It was caused by the worn DMF Flywheel. We had a new clutch & flywheel as there was a lot of play in the flywheel.

On the Dual Mass Flywheel, it is made of two parts. The inner connected to the crank & the outer where the clutch plate grips. These are connected with bushes that wear over time & allow the two parts to move independantly. This causes the problem.

If you press the clutch it removes drag & lets the flywheel float in the play area instead of at the end of the play & the problem seems less. However, if you don't press the clutch it pulls the flywheel back in relation to the crank. This is an issue as the engine management system has a flywheel sensor. Because the flywheel is now displaced in relation to the crank it causes the stumble.

When we had the new flywheel our stumble went away. I was supprised just how much play had developed over the years.

I hope that this helps all who have this fustrating issue.