Sal -the model as you describe it is tailheavy for precision flying.
For best results - determine CG (25% back from LE , at the average chord.
the average chord is at 1/2 of a wing panel measured from the tip
Example: span 73" =18.25 " from each tip.
so IF the chord at that point is oh--15" , then 25% of 15 would be , 3.75.
If after balancing it there, it still pitches heavily from a hands off level flight cruise speedtrim---- then mixin up with rudder till it is managable-you won't ever get it perfect as that just isn't part of the setup.