In my limited experience, pulsing is normally a sign that the engine is to lean, either from and airleak or wrong needle setting. Make sure you're high end needle is set 300-500 rpm below peak to the rich side.

Also, make sure your high speed needle isn't clogged. Debris in a fuel tank can sometimes lodge in the needle. Not always enough to block it, but enough to make it run lean. A very good test for this is to check the engine response to needle adjustments. A partially clogged needle valve will have little or no effect on RPM as its adjusted. If the needle is clogged, take it apart, flush it out with fuel or air, visually inspect all passages are clear, and then reassemble and retune the high end.

If it still surges after that, try slightly richening the LOW end (yes I said low end) and then retuning the high end.

Good Luck,
Brad