I found a quick and easy solution to the sloppy throttle tube issue. Buy a two liter plastic soda bottle with straight sides. Drink or dump the soda. Take a scissors and cut a section of the straight walled section about 3-1/2" wide and about as long as your throttle tube but not longer (better 1/4" or so short rather than long). Remove the end cap from the handle bar and wrap the plastic around the handle bar inside of the throttle tube and mark where it overlaps. (Insert just a little bit into the throttle tube to do this). Cut the plastic lengthwise so that there will be an 1/8" gap between the ends when wrapped around the handlebar and inside the throttle tube. Spray the plastic with chain wax (dry chain lube) on the side to go around the handle bar and slide the plastic into place inside the throttle tube. This may require a little jiggling and rotation of the throttle. Do not kink the plastic installing it as this will permanently distort the plastic and make it un-useable. Once fully inside the plastic sleeve acts as a bearing and takes up the extra gap. Operate the throttle full range several times to verify that it does not stick in any position. Mine had two spots in the rotation where I could feel a little drag. Re-install the end cap.
This plastic is harder than the throttle tube, wears well, and with a little lube will last the life of the bike. The drag disapppeared after a one hour long ride. No more slop, smooth as silk operation, and no more sticking from how the throttle was held. Enjoy, and all for 10 minutes work and 99 cents.