I would consider a bigger slide cutaway,
I believe the #7 slide is the main contributor to this hesitation coming off closed throttle. Certainly worked for me grinding to #8 when i changed needle to the N3EH. and found it just as you described.

The only thing I would change now is to have the appropriate needle that would allow the clip on the middle slot whilst keeping the same fuelling. It is currently on the top slot so there is no adjustment for warmer weather.

Standard Jetting
 

What does a 2008 ec300 come with from the factory?