kine This should go in Tech-Support (No Mods)
I think what's happening is because you only have a single huge thruster on each side, the ramp-up time is severe enough so that it not only has trouble going forward in the first place, but also oversteers when it tries to turn, creating an endless loop. Though I'd certainly classify it as a bug, it's at least in part because the thrust on that ship overall is quite unstable