Have you checked the muffler nipple and cleared it?

On the Evolution engines this frequently gets clogged with engine "goo" and causes all sorts of tuning problems.

I just jumped off another thread where someone else was having similiar problems and once he cleaned out the nipple, all of his issues went away.

You seem to be overly richening the engine to get the transition right.

This is symptomatic of lack of pressure, so it points to the nipple as well.

The Evolutions ( other than the dreaded 1.00NX ) don't usually have the transition problems that may plague say the SuperTigres.