Help propping a 300 suzuki

[willmosley]

I've got a 2004 23 cc with an Armstrong bracket, 30" 300 Suzuki. I have ran the motor at nearly every height, with both an 18.5 suzuki prop and a 19 pitch lfs4. It seems to run best with the cavitation plate about 4" up from the keel. The boat tends to porpoise anywhere at mid-rpm range. It also will fall off plane anywhere under 3800. The best mpg I can get is right under 3, where I've seen most guys are easily getting mid 3's. Top speed is around 46 mph. My prop slip numbers are not great at all. Does anyone have any recommendations? Thanks