'04 Liberty 700 misfire on top end

2004 Liberty 700 twin, 4000 miles. Runs fine off idle up to 3/4 throttle and than at that point it sounds like it hits a rev limiter, starts to studder, we have pulled the exhaust vales, cleaned, and made sure they are working, pulled the carbs, cleaned and checked jets, it acts like it's a electrical problem, I almost swear it is acing like it's detecting detonation, and adjusting timing according to protect mode, but it stated doing this out on the trail, in the middle of a tank of 91 octane gas, and I've switched ignition from premium fuel setting to regluar fuel setting, and does same thing. I don't think it's a fuel issue, or I should say I don't think its a fuel supply problem (fuel pump). When It studders at high RPM, I've pulled the choke on, and no change, but that really doesn't address if the fuel pump was weak, and not supplying enough fuel, pulling the choke on won't solve that issue. Spark plugs look right, right color, does not look like it's running to lean or to rich.
I'm wondering if whatever sensor it uses to detect detonation has failed, and that's the issue ? Can I somehow bypass the detonation sensor and run it to check to see if this is the problem ? Anyone have any ideas ?
Thanks for any info !!!

'04 Liberty 700 misfire on top end