Hi airspeed917 it sounds like the ignition battery is going dead. I had a BME102 and I ran a 4.8 1500 mah pack and I could only get two flights and the engine would either quit or would go to idle. I couldn't figure it out at first because if the engine quit on me and I landed I would restart the engine and everything seemed fine. The voltage was also fine on the pack but it just kept on doing it so I put in a 6 volt 1650 Nmhd pack on the ignition and it cured the problem . I also was only getting 5800 rpm on a RCS 26X10 prop but as soon as I changed the battery to a 6 volt my rpm's jumped to 6500rpm. I hope this helps .