I've never had a plane come off the boards that had no coupling. If it's just elevator, you're in luck. As a general rule, if it's pitching to the canopy, move your CG back. If it's pitching to the belly, move your CG forward. The difference between an okay plane and one you feel is perfect is all in the set-up, from CG & lateral balance, to prop selection, to thrust alignment, to incidence, to rates & mixes. You can spend some time tweaking, but it can also make a huge difference in how well the plane flys.