New to forum, 03 Rincon running problem

Hello to all,
I'm a new member, but a long time rider off road, on road, and track days.
Anyway,I hope someone can offer suggestions for my problem ( not that problem). I own 03 Rincon, bought it new,low miles (600 ) ,well cared for.
Was running fine last time I used it to plow snow. I may have goofed by running a tank of AV gas ( 100 oct. low lead ) through it however it ran fine on it. The machine was parked for a month or so.Next time I ran it, it started fine but will not rev past about 2000 RPM.That was 4 months ago.
My first thought was carburator, todays fuel is crappy with short shelf life..
I took the carb off and apart expecting to see a little dirt, it was surprisingly
clean, cleaned all orifices, looks good ,put back together and on bike.
No change in performance, starts right up, idles great,1/4 throttle is all you have,new gas no different, I put in new plug, did a compression test,leak down test, checked valve clearance. All good, so I took off the carb again, every thing still looks good. I did replace the diaphragm in the carb that lifts the main needle.I thought maybe the AV gas had damaged the rubber, even though it looked fine,back together,still the same.Maybe the ig. coil is the problem.I don't know but before I start throwing more parts at it, I thought I would ask here.
Has any one had a similar problem with a Rincon?
Any thoughts on using the 100 octane low lead as a cause of the problem?
Any thoughts about it in general?
Thanks in advance any one who able to respond.
Craig