I have zero experience with this engine. It is a Briggs Vanguard 16 HP V-twin.
Like I said I don't know your carb. But most of the older ones had another adjustment screw higher up on the carb somewhere. It was for idle air.Franklin2, that's kinda where I got flummoxed. There are two adjustments. one is a simple idle screw that acts on the throttle linkage. The other located very near the bottom of the carb so I'm guessing a high speed adjustment. Turning it has no discernable impact.
This tractor ran well when i got it about a year ago. So logic would seem to suggest crud in the carb.
Hey, how are you! Glad the 16G is still working for you.If none of the cleaning works, make sure you closely inspect for any hairline cracks or fractures in the carburetor body and mounting flanges. Also check for a warped flange on both the carb body and the intake base. Either could cause a vacuum leak which could cause the tractor to run better/worse as it warms up and moves around the yard.
Dad still liking the 16G you sold us, too. :fing32: