Sometimes at my uncles small track, when i go full throttle, the Reduced Engine Power light will turn on when between 5500-6500rpm.

Also, maybe related, maybe not... sometimes the engine seems to cut fuel when between 6000-6500 and will not upshift. It sounds like a whum whum whum type noise. After that, the Reduced Engine light is not on, but it has noticeably less power until I restart the motor.


Any ideas?

EDIT: Temperature during these times is between 29F and 55F... south Texas.