Do you have muffler pressure on the tank? This really helps with fuel draw. Also, you need a tach to set the engine right. I set mine to top rpm and then back off 300 to 400 rpm. Doing it by ear may be alright if you have been doing this for a few years, but it really takes a good ear and Inever did get mine tuned right that way. It's much better using the tach. If you were using a 14X8 and proped it down, you may be over reving the engine. From a 14X8 you should go 12X10 or 12X11 to keep close to the same load. For each inch you change down you add one inch of pitch. Sounds like you are over reving the enging in the air once you get it in that dive. How steep a dive are you doing anyway. You just said dive, not how steep.

Ed