it does not have an iac it is old school plane Jane engine
Does the engine have a carburetor? Most engines switched to injection around your year truck.
If you have a carberator you should be able to adjust the idle speed but the carb may need rebuilding. You can also run some fuel system cleaner in the gas tank and try to clean it.
Looking for a Used F-250 in your area?
CarGurus has 413 nationwide F-250 listings starting at $2,900.
Search Ford F-250 Questions
Ford F-250 Experts
Related Models For Sale