Did you open the choke to start the engine?  Did you leave it open?

Mine does the same thing, usually once or twice in the first couple miles, worse in cold weather. Acts like it just runs out of gas. PRI or RES always makes it go again. Seafoam makes work a little better but it still messes up now and then.  I suspect either the screen in the petc0ck (ON has the higher inlet tube up in the tank) or the valve itself, or the diaphram, or the vacuum hose (the one with the wire wrapped around it) I'm gonna try taking it apart (again) and clean the valve insides and the screen and put on a new vacuum hose. If it doesn't fix it this time I guess I'll break down and shell out the $60 for a new one, I don't reallly want to do the mod that some have done. It's great that it's automatic when it does work.

thanks guys.  Does anyone have the maintenance book that they're selling on ebay?  Will it walk me through fixes like this one?

Yes, sort of. My Clymer manual shows how to remove the fuel filter and valve, clean the screen and reinstall it.
It doesn't show how to take it apart - it's not hard to do.
Remove 4 screws on the vacuum(back) side. Carefully clean and inspect the diaphragm for any pinholes that might leak vacuum or let fuel get into the vacuum side and into the line from the carb. If the diaphragm is damaged, I don't think we can get it separately, have to buy the whole unit.