fuel pressure regulator? maybe youre running really rich so not able to burn off all the gas into the engine = misfire?... lots of vxers have had to replace their FPRs (including me) dont know that your symptoms are perfectly inline with the common ones for the FPR replaced.. but one of my issues was bad starting and i found that giving a little gas on start up helped that.. so maybe? im talkin out of my hind quarters right.. but its worth a shot.. they sell for about $50 new i beleive, DIY install