I'm with DMac, sounds like the carbs need to be cleaned again... paying particular attention to the jets. If you have been running Seafoam in it lately, it could be that it has cleaned a piece of crap loose and it's got stuck in your jets. Although, it might be as simple as some junk in your line. If you have an inline filter, check that out first. It maybe that you just have a bunch of sediment sucked up in there.