My 2001 Vulcan 1500 Fi always starts right off and idles well hot. The issue is that the colder the morning, it goes like this: after start, the engine will idle at an elevated speed and after about 10 seconds or so, will idle down to a very slow rpm and begin to miss and stumble. Sounds like a vintage tractor hitting about every 10 revs. I have to crack the throttle a little or the engine will finally stall. After it warms up, it idles fine. Runs above idle fine.
On a possibly related note, I seem to be getting a little lower overall gas mileage (from 48-50 mpg to 40-45). No other symptoms are noted, runs strong and smooth when hot.
These symptoms seem to indicate the ISC valves are working as well as the temperature sensor.
Anybody run into this before?