AVB is right, gasket first then metering diaphragm. Which kit did you install, K10-SDC? Don't remove the Welch Plug if you don't have the tools to punch a new Welch plug back. Welch plug is mainly used to cover the low jets chamber which you said it idle properly means there is no blockage inside the Welch plug. When revs, then you have the problem. The problem is on the H jet. Remove the H mixture screw and squirt with carby cleaner and observe in the venturi if the cleaner coming through the hi jet and shouldn't coming out to the metering check valve. If the cleaner is coming back through the check valve, the check valve might be damaged due to high compressed air.
CM
