Maybe this will help (if I understand your question).
To cruise at 3000 feet.
CJ4 On runway:
Set you altitude with the Altitude knob, 3000 feet.
Click VS, Vertical climb speed, 2000 feet per min.
Click AP, Auto Pilot.
Brake off.
Throttle to max.
CJ4 will lift off and climb to 3000 feet and then maintain
that altitude.
