Sounds like someone that didn't know their |removethispart|@$$ from a screwdriver adjusted the wrong screws on the carb.
If you look at the carb, down low from the passenger fender looking across in front of the battery where the throttle cable goes, there are 2 screws. The rear one towards the firewall is the warm idle screw. The other is forward and just slightly higher than that. You can just barely see is. A bracket is in the way.
With the engine cold, first thing in the morning, start the Sami with the hood open. Adjust the front screw in until you hear the idle smooth out and get a little higher, try not to take your time on that because you might end up on the warm idle circuit. when the engine warms up, adjust the rear screw out just a little, make sure the throttle cable doesn't have any tension on it. If it does, loosen the outer locknut and give just a little slack to the cable, about 1/4" up and down play in the middle of it's free length.
That should help take care of it, the only other potential issue is whther the timing is out.