Wear on the 3d cam is compensated for with adjustments. There is a setscrew under a cap on the side of the unit that will move the stylus support pin to a different location compared to the rack position. However, this is not a DIY. It needs to be sent to a specialist and put on a flow bench. You may want to try enriching the main rack with shims under the baro, then go back and adjust the idle circuit. Leaking delivery valves or a bad injector/s would be more likely a cause if everything else has been checked. (Timing, points, linkage, fuel pressure, vacuum leaks, compression, etc)