try switching plugs or replacing them. check your intakes, make sure that there is no cracks in them especially the side that's cold. That may be why the slide is sticking, its not getting enough fuel thru your carb to keep the slide lubricated. Had a similar issue, one side wasnt getting warm and ended up being a cracked intake. Once i fixed it the slide was sticking a little and would take a while to come off a rev. I stuck my finger in there and lubed it up with some oil wich helped but it kinda fixed itself once i ran it a few times due to the mix traveling thru the carb and lubing it.