Check my throttle linkage

^^All good suggestions, plus one more thing to check: It looks like your cable bracket still may be a bit too low- remember, the throttle linkage travels in an arc, the cable pulls in a straight line. If the cable is low, it takes more force to pull the linkage over that "hump", then pops the rest of the way open; similar to what you're describing.
And don't fret the "cable stop" thing- the main thing is that your throttles open all the way.