Jon,
I have a RAM500 that I fly in Denver. I had to slow the acceleration down to about 6-7 seconds to keep it from flaming out with fast full throttle. My WREN Super Sport had to be increased to about 5 seconds. The Super Sport had a weird noise when I went from full throttle to idle power rapidly. I video taped that noise and after WREN viewing they had me slow the deceleration till noise disappeared.
I have made 2 test runs with a Merlin100 in my scratch built F-94C and it handled the altitude with out of the box settings. The second run was high speed taxi test at Arvada field.
I have helped others who were flaming out on acceleration, but don't remember the engines they were using.
I thought the power loss at our altitude (5700ft) was more like 15% but not sure.
Jon, I think I bought a F-86D from you several years ago but not sure on that either. It is still sitting in my basement.