Time to clutch a few straws....
Check that the rubber grip is not binding at either end.
If you have had the throttle off, make sure the plastic lip is seated correctly inside the switch gear halves. Make sure that there is some side to side play.
Check it has free play in both cables.
Unlatch the cable from the throttle (you have to unlatch the bottom end first) Reconnect bottom end and then pull the cable to accelerate from the top end. Does it snap back ?
Remember that there are two cables. One could be dragging and the other is ok.
Check the cable at the pulley end. Make sure the cable nipples are seated correctly and that the cable sits correctly in the groove. Make sure that nothing is interfering with free movement. It's been 17 years since I parted with my 1100 - but I seem to remember an issue with mine - the cable adjuster bracket had been bent and the cable was exiting at a slight angle so it was binding. Something like that. Take a good look. Note that if there is no free play that all that happens is that pulley assembly is pulled up towards the handlebars - which I guess is what happened to mine with a previous owner.
