first off, you are describing what sounds like a spitfire mk1, hurri mk1, or any other carburated plane, the engine cuts off in these planes when doing negative G maneuvers
for the throttle on the keyboard ( not keypad ) use the - & = keys ( beside the numbers at the top)
the +&- keys on the numberpad only mess with prop / RPM's
upon taking off raise your gear hit the G key, don't pull up so abruptly trying to climb to gain altitude quickly, slowly let the plane gain speed and climb out.......
go to the Training Arena and look on roster for a trainer, if one is not available ask on text channel if someone could watch you take off and give you an asessment, also make sure you have your stick properly calibrated in windows and in the game.......
you can reach me at TequilaChaser(at)flyaceshigh.com if you would like to hook up with me or reach all the trainers at Trainers(at)flyaceshigh.com