Well.....just throwing this out there. I had a similar issues a few years ago with my 88. I had a bad battery/alternator issue going on. It would start and run fine then die a few miles from home..if that. Had to get a battery out of my ST1100 to get it back home. I finally bought a new battery and volt meter. Is your alternator putting out the correct voltage? I finally put the meter on mine and noticed the output on the alternator would be good at times and not good at other times. When not good the bike would run for a while and die.