4 degrees of down thrust would not even begin to generate the pitching up with power issues this plane has. 4 degrees of up thrust would make for a lot of upwards pitching but not enough to go vertical without something else influencing the plane. Too much back thumb on the elevator, expo the wrong direction with too much thumb, too much up trim, horizontal stab incidence, or a throttle-elevator mix left in the radio from another plane.

Pitching either up or down with power application is always an engine thrust issue but it can be combined with other factors to make it better or worse. It's the first thing I check during the first flight, with the next being the center of gravity. If I land a plane with good thrust response and there is any elevator trim present to maintain level flight at a medium flight speed after the first flight the trim direction tells me what I have to do with CG. Up trim means it's nose heavy while down trim means tail heavy. After those are dialed in I can go to work on other more subtle trims and offsets.

A seriously aft CG makes the plane difficult to control because each control input often have to be greater than the last one to reverse the condition. Planes can get out of control quickly, or be highly reactive to small control inputs. Landings can be quite difficult because the plane would have to be horsed onto the runway. Once past neutral stability things get dangerous. A seriously nose heavy plane has to be landed fast or it would stall before the wheels were close enough to do any good. Too much up elevator is required to hold the nose up, generating a lot of drag and slowing the plane down, generally at a height a lot higher than you wanted it to slow down. The word "snap" comes to mind.