Lumpy starting
 

A6 2.0 multitronic 2008

I know I know. Lots of posts about poor starting audi's when hot. But mine is a bit different to all of those I have read about on here..
Right when cold it start on the button purrs like a 😺,
When hot it's like it's only firing up on one cylinder engine jumps around then quickly settles down to it usual purr..
Took it to my local mechanic when it was hot and they started it several times and after about the 5th time there was a horrible clanging like something attached to flywheel is trying to fling itself off...
Shut it off and after they suckled in enough air to fill a hot air balloon said they think it might be gearbox? Anybody know for sure