My GV developed a sputter

[Spwoody]

Recently my 2009 Grand Vista 250 (2100 miles) has developed a sputter at idle. It sounds as though it is going to stall, but does not quite stall. I have tried adjusting the idle speed and either it idles to high or to low and stalls. Can't seem to get it right. It was time for oil change so I did that and changed the spark plug. Neither of these helped. The bike also revs really high when started from cold and seems to take a while to come down to a "normal" idle. It has not sat much during our mild winter months; rode a few times a month during winter months, so gas should be fine. If anyone has any suggestions, I am willing to try just about anything.

[zombie]

Bad gas! Add a double dose of Sea Foam, and adjust the Idle MIX screw to get the best idle. After running the tank out you may need to adjust again. Fuel containing Ethanol spoils within 2 months of sitting. Even quicker in Humid or damp conditions.

[Doug9678]

When its cold my GV takes a couple of minutes to idle down. I use only premium gas with no ethanol in it.

[zombie]

I would check EVERYWHERE for a vacuum leak. It sounds like it is leaking air somewhere. Most likely the intake coupler.

[Spwoody]

Thanks for all of the replies. I did end up finding an air tube that I must have knocked off when removing the seat to change the spark plug. Reattached the tube and everything works fine now.

[zombie]

Super cool.