I don't agree with the red-hot valves, either. There is too much heat transfer out of the engine for that to happen with your truck. Your rough-idle condition could be related to the heat-riser valve being closed and heating the intake mixture too much for low speed operation. But more likely, it is a fuel mixture matter: idle fuel adjustment, float level, valve adjustment, maybe a vacuum leak. Stuck heat-risers can usually be freed up as described by Wrenchbender, but with your COE, that may be more difficult than with a conventional cab. If the engine idles reasonably well, with or without choke, you don't have a serious valve issue- maybe adjustment is in order.
In your area, unless you run the truck in the mountains during the winter, I don't think you could tell if the heat-riser is working or not after the engine warms up. If it is stuck open, you might get rough idle and stalling during warm-up, or possibly carburetor icing and closed-throttle stalling before the engine reaches normal temperature. Off-idle operation most often is normal even with carburetor ice.
Harvester
