Hi Keith,
Your problem is that your spinnaker pole is too short and your spinnaker is too vertical. The force vector from the spinnaker is too close to horrizontal and this makes any boat pitchpole. A proper length pole will lay the spinnaker back at the head so that so that the force vector from the spinaker lifts the bows as well as well as pulls the boat forward. A few more feet of pole length makes all the difference in the world in boat behavior with a spinnaker.
Bill