Originally Posted by ridenm
Had a similar problem on a Honda motocrosser back when I rode an arenacross BITD. After much frustration and loss of confidence we found evidence that the carb slide had a burr that was catching in its track. This was a flat-slide carb, and I don't know what carb you are dealing with, but if you find no evidence of the cable hanging up (far more likely) look for signs of scuffing on the slide and its path.
I will pull the carb apart today and check for any stiction. This one has really got me baffled, the throttle cable seems fine although I have not removed it from the bike to give it a complete visual. I will get that done today.
Thanks for the input.