ATV newbie recently acquired a 1999 Polaris Xplorer 400 4X4. It seems to start rough and idle rough, then sometimes will stall out if you let off the throttle too much. Once running (medium to full throttle), it seems to run well. Also has issues with starting once the gas tank gets below a 1/4 tank. Any suggestions on where to start?

I've read about the reverse limiter, but I can't seem to find its location on this ATV.