Engine Misfire at Altitude.

[cbxmike]

I was recently told that it takes a min of 52psi oil pressure to get the waste gate to fully close. Check to see if your hot oil pressures are at least that and adjust if needed to get full waste gate operation. Could be part of your issue possibly. My rear engine is at 46psi currently and I get some bootstrapping at around 16,000ft. I need to adjust mine up a bit. May not be what you’re experiencing but worth checking all the same.

Mike