I believe you took offense when none was intended. I guess my point was, if it's just a knock-around, pieced-together project, it's going to be tough to get it to fly just right.

OK, let me give this a sincere effort... I would guess the horizontal stab has negative incidence in it. You can trim for level flight at one throttle setting, but the second you add more power, it's going to force the tail down, and shoot up again. The problem you are describing sounds like the horizontal stab has both negative incidence, and is probably twisted a little bit, causing the rolling effect you are mentioning.