On two seperate occassions, my 1988 HD FXRS seemed to lose power suddenly on the freeway - It went from 70 mph to 15 mph without shifting down from fifth. I attempted shifting through all gears but nothing happened. I limped it off the freeway and after continuing to shift through all the gears for about a mile, the gears seemed to start to engage again and I was able to ride again normally. Now I also notice that once I shift into third gear or higher, if I gun the throttle, the rpm rev way up but the bike takes a couple of seconds before it will accelerate to the appropriate speed. Any ideas?