I have had this odd problem on my bike ('96 600s) for a little while. It acts like it is running out of gas when it has gas. I switch to reserve and it goes away, then goes back. I run it in priming mode to get home.
I check the petcock, perfectly clean, internals look fine. On the '96 there wasn't an inline fuel filter after the tank.
Any ideas? I can't ride long distances at all.