I'm losing power occasionally between 8k and 10k rpm. Redline is 11k. I tested it in first today and it didn't do anything abnormal. But in second and third and fourth once it gets to 8,000 rpm, or sometimes 8,500 rpm it loses power, and almost can't keep the same speed, and get very jerky. It revs up fine in neutral, no problems there. Any idea what it is? Anything i can check myself?