[Cal Metal]

No master of the IDFs, that's for sure.

How about this. Disconnect the linkage to the carbs and adjust each barrel for optimal idle, using the idle/mixture control. When they are optimally set (highest rpm), reconnect the linkage and use the idle set screw (should be just one) to adjust idle speed to the desired level. That adjuster should increase the opening on all the carbs simultaneously. I know the IDF has an air control adjuster which is used to balance out the barrels of each carb. This is more of a fine tuning issue which you might want to pursue. Try the former first, though, and see what you get.