You are way overpropped: go to a 14 x 6 as was mentioned earlier. I had an MVVS 91 on this plane. The MVVS likes big props, but this combination had problems taking off on a 13 x 8. It just would not lift without using one and a half runways. When I changed the prop to a 14 x 6 and got it to lift it was so sensitive to elevator that I (barely) managed a cicuit to get it down safely. I cut down the elevator movement by about half again and it was flyable but so snappy at the bottom of loops that you could not do many manoeuvres.

I then reduced the movement some more until I noticed the limitation - just a few degrees - and it was almost alright. I did give it a chance with CG changes, et cetera but the plane was never a pleasure to fly (as far as I was concerned) and was always hard work. Eventually I lost it in a crash. Yes, you guessed it - snapped out of the bottom of a loop.