[SleepyC]

Did you check the wing incidence on the main wings and the stabs?
I'd start there, and then start messing with the thrust.
I'm just saying this because I went through the same thing last summer with a BRAND X Yak.

After a fellow modeler and FG member with many more years of expierence told me to check, I couldn't believe it.

My stabs were both messed up.
the one was at +1.5 deg and the other was +2 deg.

The main wings were better 0 deg and + 1 deg.

After I fixed this the plane just needed the 3 deg of right thrust.
I'd say start with checking that!
Hope that helps!