Are you saying you get fuel cut at 8100? Check spark plug wires, and take the distributor cap off and inspect the cap and rotor and for any loose or corroded connections. I assume you run stock timing - if not put it back to stock. What fuel are you using? Make sure it's always premium high octane. Are you sure your catalyst isn't clogged? You can disconnect the A-pipe from the catalyst and take it for a spin, and see if exhaust backpressure is causing the condition. Hook up a secondary Tach, like a VAFC or an analog gauge to make sure your stock tach is accurate, they usually aren't the best.