I’ll re-fit the cable going right back to the beginning and set up the carb ends before fitting either of the other ends and work back from there… I’ll repot back.
I think that with this issue you are best to connect it up with the carbs off the bike at one side on a small table/stand and the cable in the air. This allows you to see exactly how the slides are positioned and that they fully raise and lower. You can also check if there is a problem with range of movement in the various sections of cable. You can do this with the oil pump cable connected as well.
As far as the Throttle tube goes, I recently had one that would only give about 23mm of cable travel, that left the slides either too far down or too far up, you need at least 28mm of cable travel, more like 30mm minimum to give a tad of adjustment and free play!
Not absolutely certain of that Throttle tube id, but I thought it was OE, probably 1GU, the superceeded part. Anyway, the cure for that was to file back the plastic stop bit 10mm, and that gave enough cable travel between the closed stop and the full throttle stop of the tube in its twistgrip casting.
You should be able to find where your problem is by doing the carbs off and connecting it all up.
Cheers
5port