Okay, I've had time to try v3 of the FDE, and once again, thanks for taking the time to look into this. Unfortunately, the inability to settle the aircraft into level flight persists. What I expect to happen is that for a fixed throttle setting - the aircraft noses up, the speed decreases, the lift decreases and so the nose then angles down, and the aircraft starts to descend ... as a result of that , the speed increases, lift increases, and the aircraft starts to ascend again. I believe the correct aerodynamic term for this oscillation is phugoid, or fugoid.
The problem with the A-7 ( and the A-6 and EA-6B too ) is that this oscillation doesn't seem to happen. You set the trim upwards, and it might pitch up for a while, lose speed, then pitch down and although the airspeed then increases, it just keeps heading downwards. You then have to adjust the pitch trim up by a notch, then another notch..and another...and before you know it, you are in a constant climb. It's just constant 'trim up' and 'trim down' and can not be set to fly level. I haven't come across this sort of issue with other models.
So, thanks for your efforts, but the A-7 remains too much of a chore to use.