I'm not sure if foaming was my problem anymore, I made room for 1/4" of foam around the tank and put a felt clunk in it and those changes made absolutely no difference at all. I'm thinking now that it may be some type of interference or radio problem within the plane. Whatever is happening affects both the throttle and elevator channels at the same time and only lasts for a few seconds. Aileron and rudder channels never seem to be affected. I did another range check last night with the engine running and had no problems and the engine runs great on the ground, no bubbles in the lines or anything like that. I guess my first move will be to try a different receiver even though the one in it is a brand new Futaba. Frustrating!